diff --git a/dom/base/nsDOMWindowUtils.cpp b/dom/base/nsDOMWindowUtils.cpp
index ac3c7784bc..05e4eb27bd 100644
--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -842,7 +842,7 @@ nsDOMWindowUtils::SendWheelEvent(float aX,
     return NS_ERROR_NULL_POINTER;
   }
 
-  WidgetWheelEvent wheelEvent(true, NS_WHEEL_WHEEL, widget);
+  WidgetWheelEvent wheelEvent(true, eWheel, widget);
   wheelEvent.modifiers = nsContentUtils::GetWidgetModifiers(aModifiers);
   wheelEvent.deltaX = aDeltaX;
   wheelEvent.deltaY = aDeltaY;
@@ -1943,7 +1943,7 @@ nsDOMWindowUtils::SendQueryContentEvent(uint32_t aType,
       message = eQueryCaretRect;
       break;
     case QUERY_TEXT_RECT:
-      message = NS_QUERY_TEXT_RECT;
+      message = eQueryTextRect;
       break;
     case QUERY_EDITOR_RECT:
       message = eQueryEditorRect;
@@ -1998,7 +1998,7 @@ nsDOMWindowUtils::SendQueryContentEvent(uint32_t aType,
     case eQueryCaretRect:
       queryEvent.InitForQueryCaretRect(aOffset, useNativeLineBreak);
       break;
-    case NS_QUERY_TEXT_RECT:
+    case eQueryTextRect:
       queryEvent.InitForQueryTextRect(aOffset, aLength, useNativeLineBreak);
       break;
     default:
diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index b0e0c09955..71041dc7ad 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -1431,8 +1431,8 @@ nsGlobalWindow::CleanUp()
     }
 
 #ifdef MOZ_B2G
-    DisableNetworkEvent(NS_NETWORK_UPLOAD_EVENT);
-    DisableNetworkEvent(NS_NETWORK_DOWNLOAD_EVENT);
+    DisableNetworkEvent(eNetworkUpload);
+    DisableNetworkEvent(eNetworkDownload);
 #endif // MOZ_B2G
 
     if (mIdleService) {
@@ -14314,13 +14314,13 @@ nsGlobalWindow::EnableNetworkEvent(EventMessage aEventMessage)
   }
 
   switch (aEventMessage) {
-    case NS_NETWORK_UPLOAD_EVENT:
+    case eNetworkUpload:
       if (!mNetworkUploadObserverEnabled) {
         mNetworkUploadObserverEnabled = true;
         os->AddObserver(mObserver, NS_NETWORK_ACTIVITY_BLIP_UPLOAD_TOPIC, false);
       }
       break;
-    case NS_NETWORK_DOWNLOAD_EVENT:
+    case eNetworkDownload:
       if (!mNetworkDownloadObserverEnabled) {
         mNetworkDownloadObserverEnabled = true;
         os->AddObserver(mObserver, NS_NETWORK_ACTIVITY_BLIP_DOWNLOAD_TOPIC, false);
@@ -14342,13 +14342,13 @@ nsGlobalWindow::DisableNetworkEvent(EventMessage aEventMessage)
   }
 
   switch (aEventMessage) {
-    case NS_NETWORK_UPLOAD_EVENT:
+    case eNetworkUpload:
       if (mNetworkUploadObserverEnabled) {
         mNetworkUploadObserverEnabled = false;
         os->RemoveObserver(mObserver, NS_NETWORK_ACTIVITY_BLIP_UPLOAD_TOPIC);
       }
       break;
-    case NS_NETWORK_DOWNLOAD_EVENT:
+    case eNetworkDownload:
       if (mNetworkDownloadObserverEnabled) {
         mNetworkDownloadObserverEnabled = false;
         os->RemoveObserver(mObserver, NS_NETWORK_ACTIVITY_BLIP_DOWNLOAD_TOPIC);
diff --git a/dom/base/nsQueryContentEventResult.cpp b/dom/base/nsQueryContentEventResult.cpp
index 6f3a830652..7ffd2ead03 100644
--- a/dom/base/nsQueryContentEventResult.cpp
+++ b/dom/base/nsQueryContentEventResult.cpp
@@ -58,7 +58,7 @@ nsQueryContentEventResult::GetTentativeCaretOffset(uint32_t* aOffset)
 static bool IsRectEnabled(EventMessage aEventMessage)
 {
   return aEventMessage == eQueryCaretRect ||
-         aEventMessage == NS_QUERY_TEXT_RECT ||
+         aEventMessage == eQueryTextRect ||
          aEventMessage == eQueryEditorRect ||
          aEventMessage == eQueryCharacterAtPoint;
 }
diff --git a/dom/events/ContentEventHandler.cpp b/dom/events/ContentEventHandler.cpp
index 73dd49e2dc..084743070a 100644
--- a/dom/events/ContentEventHandler.cpp
+++ b/dom/events/ContentEventHandler.cpp
@@ -802,7 +802,7 @@ ContentEventHandler::HandleQueryContentEvent(WidgetQueryContentEvent* aEvent)
       return OnQueryTextContent(aEvent);
     case eQueryCaretRect:
       return OnQueryCaretRect(aEvent);
-    case NS_QUERY_TEXT_RECT:
+    case eQueryTextRect:
       return OnQueryTextRect(aEvent);
     case eQueryEditorRect:
       return OnQueryEditorRect(aEvent);
@@ -1330,7 +1330,7 @@ ContentEventHandler::OnQueryCharacterAtPoint(WidgetQueryContentEvent* aEvent)
                                 GetLineBreakType(aEvent));
   NS_ENSURE_SUCCESS(rv, rv);
 
-  WidgetQueryContentEvent textRect(true, NS_QUERY_TEXT_RECT, aEvent->widget);
+  WidgetQueryContentEvent textRect(true, eQueryTextRect, aEvent->widget);
   textRect.InitForQueryTextRect(offset, 1, aEvent->mUseNativeLineBreak);
   rv = OnQueryTextRect(&textRect);
   NS_ENSURE_SUCCESS(rv, rv);
diff --git a/dom/events/ContentEventHandler.h b/dom/events/ContentEventHandler.h
index a2b1043a63..2707789e4a 100644
--- a/dom/events/ContentEventHandler.h
+++ b/dom/events/ContentEventHandler.h
@@ -48,7 +48,7 @@ public:
   nsresult OnQueryTextContent(WidgetQueryContentEvent* aEvent);
   // eQueryCaretRect event handler
   nsresult OnQueryCaretRect(WidgetQueryContentEvent* aEvent);
-  // NS_QUERY_TEXT_RECT event handler
+  // eQueryTextRect event handler
   nsresult OnQueryTextRect(WidgetQueryContentEvent* aEvent);
   // eQueryEditorRect event handler
   nsresult OnQueryEditorRect(WidgetQueryContentEvent* aEvent);
diff --git a/dom/events/EventListenerManager.cpp b/dom/events/EventListenerManager.cpp
index 2cf5a5a89b..0369480452 100644
--- a/dom/events/EventListenerManager.cpp
+++ b/dom/events/EventListenerManager.cpp
@@ -317,13 +317,13 @@ EventListenerManager::AddEventListenerInternal(
           kAllMutationBits : MutationBitForEventType(aEventMessage));
     }
   } else if (aTypeAtom == nsGkAtoms::ondeviceorientation) {
-    EnableDevice(NS_DEVICE_ORIENTATION);
+    EnableDevice(eDeviceOrientation);
   } else if (aTypeAtom == nsGkAtoms::ondeviceproximity || aTypeAtom == nsGkAtoms::onuserproximity) {
-    EnableDevice(NS_DEVICE_PROXIMITY);
+    EnableDevice(eDeviceProximity);
   } else if (aTypeAtom == nsGkAtoms::ondevicelight) {
-    EnableDevice(NS_DEVICE_LIGHT);
+    EnableDevice(eDeviceLight);
   } else if (aTypeAtom == nsGkAtoms::ondevicemotion) {
-    EnableDevice(NS_DEVICE_MOTION);
+    EnableDevice(eDeviceMotion);
 #ifdef MOZ_B2G
   } else if (aTypeAtom == nsGkAtoms::onmoztimechange) {
     nsCOMPtr<nsPIDOMWindow> window = GetTargetAsInnerWindow();
@@ -333,12 +333,12 @@ EventListenerManager::AddEventListenerInternal(
   } else if (aTypeAtom == nsGkAtoms::onmoznetworkupload) {
     nsCOMPtr<nsPIDOMWindow> window = GetTargetAsInnerWindow();
     if (window) {
-      window->EnableNetworkEvent(NS_NETWORK_UPLOAD_EVENT);
+      window->EnableNetworkEvent(eNetworkUpload);
     }
   } else if (aTypeAtom == nsGkAtoms::onmoznetworkdownload) {
     nsCOMPtr<nsPIDOMWindow> window = GetTargetAsInnerWindow();
     if (window) {
-      window->EnableNetworkEvent(NS_NETWORK_DOWNLOAD_EVENT);
+      window->EnableNetworkEvent(eNetworkDownload);
     }
 #endif // MOZ_B2G
   } else if (aTypeAtom == nsGkAtoms::ontouchstart ||
@@ -382,8 +382,8 @@ EventListenerManager::AddEventListenerInternal(
       window->SetHasMouseEnterLeaveEventListeners();
     }
 #ifdef MOZ_GAMEPAD
-  } else if (aEventMessage >= NS_GAMEPAD_START &&
-             aEventMessage <= NS_GAMEPAD_END) {
+  } else if (aEventMessage >= eGamepadEventFirst &&
+             aEventMessage <= eGamepadEventLast) {
     nsPIDOMWindow* window = GetInnerWindowForTarget();
     if (window) {
       window->SetHasGamepadEventListener();
@@ -425,11 +425,11 @@ bool
 EventListenerManager::IsDeviceType(EventMessage aEventMessage)
 {
   switch (aEventMessage) {
-    case NS_DEVICE_ORIENTATION:
-    case NS_DEVICE_MOTION:
-    case NS_DEVICE_LIGHT:
-    case NS_DEVICE_PROXIMITY:
-    case NS_USER_PROXIMITY:
+    case eDeviceOrientation:
+    case eDeviceMotion:
+    case eDeviceLight:
+    case eDeviceProximity:
+    case eUserProximity:
       return true;
     default:
       break;
@@ -446,17 +446,17 @@ EventListenerManager::EnableDevice(EventMessage aEventMessage)
   }
 
   switch (aEventMessage) {
-    case NS_DEVICE_ORIENTATION:
+    case eDeviceOrientation:
       window->EnableDeviceSensor(SENSOR_ORIENTATION);
       break;
-    case NS_DEVICE_PROXIMITY:
-    case NS_USER_PROXIMITY:
+    case eDeviceProximity:
+    case eUserProximity:
       window->EnableDeviceSensor(SENSOR_PROXIMITY);
       break;
-    case NS_DEVICE_LIGHT:
+    case eDeviceLight:
       window->EnableDeviceSensor(SENSOR_LIGHT);
       break;
-    case NS_DEVICE_MOTION:
+    case eDeviceMotion:
       window->EnableDeviceSensor(SENSOR_ACCELERATION);
       window->EnableDeviceSensor(SENSOR_LINEAR_ACCELERATION);
       window->EnableDeviceSensor(SENSOR_GYROSCOPE);
@@ -476,19 +476,19 @@ EventListenerManager::DisableDevice(EventMessage aEventMessage)
   }
 
   switch (aEventMessage) {
-    case NS_DEVICE_ORIENTATION:
+    case eDeviceOrientation:
       window->DisableDeviceSensor(SENSOR_ORIENTATION);
       break;
-    case NS_DEVICE_MOTION:
+    case eDeviceMotion:
       window->DisableDeviceSensor(SENSOR_ACCELERATION);
       window->DisableDeviceSensor(SENSOR_LINEAR_ACCELERATION);
       window->DisableDeviceSensor(SENSOR_GYROSCOPE);
       break;
-    case NS_DEVICE_PROXIMITY:
-    case NS_USER_PROXIMITY:
+    case eDeviceProximity:
+    case eUserProximity:
       window->DisableDeviceSensor(SENSOR_PROXIMITY);
       break;
-    case NS_DEVICE_LIGHT:
+    case eDeviceLight:
       window->DisableDeviceSensor(SENSOR_LIGHT);
       break;
     default:
@@ -516,9 +516,9 @@ EventListenerManager::RemoveEventListenerInternal(
   uint32_t typeCount = 0;
   bool deviceType = IsDeviceType(aEventMessage);
 #ifdef MOZ_B2G
-  bool timeChangeEvent = (aEventMessage == NS_MOZ_TIME_CHANGE_EVENT);
-  bool networkEvent = (aEventMessage == NS_NETWORK_UPLOAD_EVENT ||
-                       aEventMessage == NS_NETWORK_DOWNLOAD_EVENT);
+  bool timeChangeEvent = (aEventMessage == eTimeChange);
+  bool networkEvent = (aEventMessage == eNetworkUpload ||
+                       aEventMessage == eNetworkDownload);
 #endif // MOZ_B2G
 
   for (uint32_t i = 0; i < count; ++i) {
diff --git a/dom/events/EventNameList.h b/dom/events/EventNameList.h
index 0233e6c1e5..322a397415 100644
--- a/dom/events/EventNameList.h
+++ b/dom/events/EventNameList.h
@@ -303,11 +303,11 @@ EVENT(mozfullscreenerror,
       EventNameType_HTML,
       eBasicEventClass)
 EVENT(mozpointerlockchange,
-      NS_POINTERLOCKCHANGE,
+      ePointerLockChange,
       EventNameType_HTML,
       eBasicEventClass)
 EVENT(mozpointerlockerror,
-      NS_POINTERLOCKERROR,
+      ePointerLockError,
       EventNameType_HTML,
       eBasicEventClass)
 EVENT(pointerdown,
@@ -426,7 +426,7 @@ EVENT(waiting,
       EventNameType_HTML,
       eBasicEventClass)
 EVENT(wheel,
-      NS_WHEEL_WHEEL,
+      eWheel,
       EventNameType_All,
       eWheelEventClass)
 EVENT(copy,
@@ -477,11 +477,11 @@ FORWARDED_EVENT(scroll,
                 eBasicEventClass)
 
 WINDOW_EVENT(afterprint,
-             NS_AFTERPRINT,
+             eAfterPrint,
              EventNameType_XUL | EventNameType_HTMLBodyOrFramesetOnly,
              eBasicEventClass)
 WINDOW_EVENT(beforeprint,
-             NS_BEFOREPRINT,
+             eBeforePrint,
              EventNameType_XUL | EventNameType_HTMLBodyOrFramesetOnly,
              eBasicEventClass)
 BEFOREUNLOAD_EVENT(beforeunload,
@@ -536,37 +536,37 @@ WINDOW_EVENT(unload,
              eBasicEventClass)
 
 WINDOW_ONLY_EVENT(devicemotion,
-                  NS_DEVICE_MOTION,
+                  eDeviceMotion,
                   EventNameType_None,
                   eBasicEventClass)
 WINDOW_ONLY_EVENT(deviceorientation,
-                  NS_DEVICE_ORIENTATION,
+                  eDeviceOrientation,
                   EventNameType_None,
                   eBasicEventClass)
 WINDOW_ONLY_EVENT(deviceproximity,
-                  NS_DEVICE_PROXIMITY,
+                  eDeviceProximity,
                   EventNameType_None,
                   eBasicEventClass)
 WINDOW_ONLY_EVENT(userproximity,
-                  NS_USER_PROXIMITY,
+                  eUserProximity,
                   EventNameType_None,
                   eBasicEventClass)
 WINDOW_ONLY_EVENT(devicelight,
-                  NS_DEVICE_LIGHT,
+                  eDeviceLight,
                   EventNameType_None,
                   eBasicEventClass)
 
 #ifdef MOZ_B2G
 WINDOW_ONLY_EVENT(moztimechange,
-                  NS_MOZ_TIME_CHANGE_EVENT,
+                  eTimeChange,
                   EventNameType_None,
                   eBasicEventClass)
 WINDOW_ONLY_EVENT(moznetworkupload,
-                  NS_NETWORK_UPLOAD_EVENT,
+                  eNetworkUpload,
                   EventNameType_None,
                   eBasicEventClass)
 WINDOW_ONLY_EVENT(moznetworkdownload,
-                  NS_NETWORK_DOWNLOAD_EVENT,
+                  eNetworkDownload,
                   EventNameType_None,
                   eBasicEventClass)
 #endif // MOZ_B2G
@@ -593,11 +593,11 @@ DOCUMENT_ONLY_EVENT(readystatechange,
                     EventNameType_HTMLXUL,
                     eBasicEventClass)
 DOCUMENT_ONLY_EVENT(selectionchange,
-                    NS_SELECTION_CHANGE,
+                    eSelectionChange,
                     EventNameType_HTMLXUL,
                     eBasicEventClass)
 DOCUMENT_ONLY_EVENT(visibilitychange,
-                    NS_VISIBILITY_CHANGE,
+                    eVisibilityChange,
                     EventNameType_HTMLXUL,
                     eBasicEventClass)
 
@@ -688,19 +688,19 @@ NON_IDL_EVENT(speakerforcedchange,
  // This shouldn't be used by web/xul apps.  "compositionupdate" should be
  // used instead.
 NON_IDL_EVENT(text,
-              NS_COMPOSITION_CHANGE,
+              eCompositionChange,
               EventNameType_XUL,
               eCompositionEventClass)
 NON_IDL_EVENT(compositionstart,
-              NS_COMPOSITION_START,
+              eCompositionStart,
               EventNameType_XUL,
               eCompositionEventClass)
 NON_IDL_EVENT(compositionupdate,
-              NS_COMPOSITION_UPDATE,
+              eCompositionUpdate,
               EventNameType_XUL,
               eCompositionEventClass)
 NON_IDL_EVENT(compositionend,
-              NS_COMPOSITION_END,
+              eCompositionEnd,
               EventNameType_XUL,
               eCompositionEventClass)
 NON_IDL_EVENT(command,
@@ -748,11 +748,11 @@ NON_IDL_EVENT(draggesture,
               EventNameType_XUL,
               eDragEventClass)
 NON_IDL_EVENT(overflow,
-              NS_SCROLLPORT_OVERFLOW,
+              eScrollPortOverflow,
               EventNameType_XUL,
               eBasicEventClass)
 NON_IDL_EVENT(underflow,
-              NS_SCROLLPORT_UNDERFLOW,
+              eScrollPortUnderflow,
               EventNameType_XUL,
               eBasicEventClass)
 
@@ -790,34 +790,34 @@ NON_IDL_EVENT(zoom,
 // Only map the ID to the real event name when MESSAGE_TO_EVENT is defined.
 #ifndef MESSAGE_TO_EVENT
 NON_IDL_EVENT(begin,
-              NS_SMIL_BEGIN,
+              eSMILBeginEvent,
               EventNameType_SMIL,
               eBasicEventClass)
 #endif
 NON_IDL_EVENT(beginEvent,
-              NS_SMIL_BEGIN,
+              eSMILBeginEvent,
               EventNameType_None,
               eSMILTimeEventClass)
 // Only map the ID to the real event name when MESSAGE_TO_EVENT is defined.
 #ifndef MESSAGE_TO_EVENT
 NON_IDL_EVENT(end,
-              NS_SMIL_END,
+              eSMILEndEvent,
               EventNameType_SMIL,
               eBasicEventClass)
 #endif
 NON_IDL_EVENT(endEvent,
-              NS_SMIL_END,
+              eSMILEndEvent,
               EventNameType_None,
               eSMILTimeEventClass)
 // Only map the ID to the real event name when MESSAGE_TO_EVENT is defined.
 #ifndef MESSAGE_TO_EVENT
 NON_IDL_EVENT(repeat,
-              NS_SMIL_REPEAT,
+              eSMILRepeatEvent,
               EventNameType_SMIL,
               eBasicEventClass)
 #endif
 NON_IDL_EVENT(repeatEvent,
-              NS_SMIL_REPEAT,
+              eSMILRepeatEvent,
               EventNameType_None,
               eSMILTimeEventClass)
 
@@ -827,29 +827,29 @@ NON_IDL_EVENT(MozAfterPaint,
               eBasicEventClass)
 
 NON_IDL_EVENT(MozScrolledAreaChanged,
-              NS_SCROLLEDAREACHANGED,
+              eScrolledAreaChanged,
               EventNameType_None,
               eScrollAreaEventClass)
 
 #ifdef MOZ_GAMEPAD
 NON_IDL_EVENT(gamepadbuttondown,
-              NS_GAMEPAD_BUTTONDOWN,
+              eGamepadButtonDown,
               EventNameType_None,
               eBasicEventClass)
 NON_IDL_EVENT(gamepadbuttonup,
-              NS_GAMEPAD_BUTTONUP,
+              eGamepadButtonUp,
               EventNameType_None,
               eBasicEventClass)
 NON_IDL_EVENT(gamepadaxismove,
-              NS_GAMEPAD_AXISMOVE,
+              eGamepadAxisMove,
               EventNameType_None,
               eBasicEventClass)
 NON_IDL_EVENT(gamepadconnected,
-              NS_GAMEPAD_CONNECTED,
+              eGamepadConnected,
               EventNameType_None,
               eBasicEventClass)
 NON_IDL_EVENT(gamepaddisconnected,
-              NS_GAMEPAD_DISCONNECTED,
+              eGamepadDisconnected,
               EventNameType_None,
               eBasicEventClass)
 #endif
diff --git a/dom/events/EventStateManager.cpp b/dom/events/EventStateManager.cpp
index be8f20b308..be62b0edb5 100644
--- a/dom/events/EventStateManager.cpp
+++ b/dom/events/EventStateManager.cpp
@@ -519,7 +519,7 @@ EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
     nsCOMPtr<nsINode> node = do_QueryInterface(aTargetContent);
     if (node &&
         (aEvent->mMessage == eKeyUp || aEvent->mMessage == eMouseUp ||
-         aEvent->mMessage == NS_WHEEL_WHEEL || aEvent->mMessage == NS_TOUCH_END ||
+         aEvent->mMessage == eWheel || aEvent->mMessage == NS_TOUCH_END ||
          aEvent->mMessage == ePointerUp)) {
       nsIDocument* doc = node->OwnerDoc();
       while (doc && !doc->UserHasInteracted()) {
@@ -727,9 +727,9 @@ EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
       keyEvent->mIsComposing = !!composition;
     }
     break;
-  case NS_WHEEL_WHEEL:
-  case NS_WHEEL_START:
-  case NS_WHEEL_STOP:
+  case eWheel:
+  case eWheelOperationStart:
+  case eWheelOperationEnd:
     {
       NS_ASSERTION(aEvent->mFlags.mIsTrusted,
                    "Untrusted wheel event shouldn't be here");
@@ -739,7 +739,7 @@ EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
         mCurrentTargetContent = content;
       }
 
-      if (aEvent->mMessage != NS_WHEEL_WHEEL) {
+      if (aEvent->mMessage != eWheel) {
         break;
       }
 
@@ -775,7 +775,7 @@ EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
   case eContentCommandScroll:
     DoContentCommandScrollEvent(aEvent->AsContentCommandEvent());
     break;
-  case NS_COMPOSITION_START:
+  case eCompositionStart:
     if (aEvent->mFlags.mIsTrusted) {
       // If the event is trusted event, set the selected text to data of
       // composition event.
@@ -800,7 +800,7 @@ EventStateManager::HandleQueryContentEvent(WidgetQueryContentEvent* aEvent)
     case eQuerySelectedText:
     case eQueryTextContent:
     case eQueryCaretRect:
-    case NS_QUERY_TEXT_RECT:
+    case eQueryTextRect:
     case eQueryEditorRect:
       if (!IsTargetCrossProcess(aEvent)) {
         break;
@@ -2579,7 +2579,7 @@ EventStateManager::DecideGestureEvent(WidgetGestureNotifyEvent* aEvent,
                                       nsIFrame* targetFrame)
 {
 
-  NS_ASSERTION(aEvent->mMessage == NS_GESTURENOTIFY_EVENT_START,
+  NS_ASSERTION(aEvent->mMessage == eGestureNotify,
                "DecideGestureEvent called with a non-gesture event");
 
   /* Check the ancestor tree to decide if any frame is willing* to receive
@@ -3024,7 +3024,7 @@ EventStateManager::PostHandleEvent(nsPresContext* aPresContext,
       }
     }
     break;
-  case NS_WHEEL_STOP:
+  case eWheelOperationEnd:
     {
       MOZ_ASSERT(aEvent->mFlags.mIsTrusted);
       ScrollbarsForWheel::MayInactivate();
@@ -3037,8 +3037,8 @@ EventStateManager::PostHandleEvent(nsPresContext* aPresContext,
       }
     }
     break;
-  case NS_WHEEL_WHEEL:
-  case NS_WHEEL_START:
+  case eWheel:
+  case eWheelOperationStart:
     {
       MOZ_ASSERT(aEvent->mFlags.mIsTrusted);
 
@@ -3064,7 +3064,7 @@ EventStateManager::PostHandleEvent(nsPresContext* aPresContext,
 
           ScrollbarsForWheel::PrepareToScrollText(this, aTargetFrame, wheelEvent);
 
-          if (aEvent->mMessage != NS_WHEEL_WHEEL ||
+          if (aEvent->mMessage != eWheel ||
               (!wheelEvent->deltaX && !wheelEvent->deltaY)) {
             break;
           }
@@ -3149,7 +3149,7 @@ EventStateManager::PostHandleEvent(nsPresContext* aPresContext,
     }
     break;
 
-  case NS_GESTURENOTIFY_EVENT_START:
+  case eGestureNotify:
     {
       if (nsEventStatus_eConsumeNoDefault != *aStatus) {
         DecideGestureEvent(aEvent->AsGestureNotifyEvent(), mCurrentTarget);
@@ -5596,7 +5596,8 @@ EventStateManager::WheelPrefs::HasUserPrefsForDelta(WidgetWheelEvent* aEvent)
 bool
 EventStateManager::WheelEventIsScrollAction(WidgetWheelEvent* aEvent)
 {
-  return WheelPrefs::GetInstance()->ComputeActionFor(aEvent) == WheelPrefs::ACTION_SCROLL;
+  return aEvent->mMessage == eWheel &&
+         WheelPrefs::GetInstance()->ComputeActionFor(aEvent) == WheelPrefs::ACTION_SCROLL;
 }
 
 bool
diff --git a/dom/events/IMEContentObserver.cpp b/dom/events/IMEContentObserver.cpp
index 019d5d6c6e..4f1fcd8475 100644
--- a/dom/events/IMEContentObserver.cpp
+++ b/dom/events/IMEContentObserver.cpp
@@ -57,8 +57,8 @@ ToChar(EventMessage aEventMessage)
       return "eQueryTextContent";
     case eQueryCaretRect:
       return "eQueryCaretRect";
-    case NS_QUERY_TEXT_RECT:
-      return "NS_QUERY_TEXT_RECT";
+    case eQueryTextRect:
+      return "eQueryTextRect";
     case eQueryEditorRect:
       return "eQueryEditorRect";
     case eQueryContentState:
diff --git a/dom/events/IMEStateManager.cpp b/dom/events/IMEStateManager.cpp
index d9231f6d11..fa07deffe9 100644
--- a/dom/events/IMEStateManager.cpp
+++ b/dom/events/IMEStateManager.cpp
@@ -137,18 +137,18 @@ static const char*
 GetEventMessageName(EventMessage aMessage)
 {
   switch (aMessage) {
-    case NS_COMPOSITION_START:
-      return "NS_COMPOSITION_START";
-    case NS_COMPOSITION_END:
-      return "NS_COMPOSITION_END";
-    case NS_COMPOSITION_UPDATE:
-      return "NS_COMPOSITION_UPDATE";
-    case NS_COMPOSITION_CHANGE:
-      return "NS_COMPOSITION_CHANGE";
-    case NS_COMPOSITION_COMMIT_AS_IS:
-      return "NS_COMPOSITION_COMMIT_AS_IS";
-    case NS_COMPOSITION_COMMIT:
-      return "NS_COMPOSITION_COMMIT";
+    case eCompositionStart:
+      return "eCompositionStart";
+    case eCompositionEnd:
+      return "eCompositionEnd";
+    case eCompositionUpdate:
+      return "eCompositionUpdate";
+    case eCompositionChange:
+      return "eCompositionChange";
+    case eCompositionCommitAsIs:
+      return "eCompositionCommitAsIs";
+    case eCompositionCommit:
+      return "eCompositionCommit";
     case eSetSelection:
       return "eSetSelection";
     default:
@@ -1147,7 +1147,7 @@ IMEStateManager::DispatchCompositionEvent(
     return;
   }
 
-  MOZ_ASSERT(aCompositionEvent->mMessage != NS_COMPOSITION_UPDATE,
+  MOZ_ASSERT(aCompositionEvent->mMessage != eCompositionUpdate,
              "compositionupdate event shouldn't be dispatched manually");
 
   EnsureTextCompositionArray();
@@ -1163,7 +1163,7 @@ IMEStateManager::DispatchCompositionEvent(
     MOZ_LOG(sISMLog, LogLevel::Debug,
       ("ISM:   IMEStateManager::DispatchCompositionEvent(), "
        "adding new TextComposition to the array"));
-    MOZ_ASSERT(aCompositionEvent->mMessage == NS_COMPOSITION_START);
+    MOZ_ASSERT(aCompositionEvent->mMessage == eCompositionStart);
     composition =
       new TextComposition(aPresContext, aEventTargetNode, tabParent,
                           aCompositionEvent);
@@ -1171,7 +1171,7 @@ IMEStateManager::DispatchCompositionEvent(
   }
 #ifdef DEBUG
   else {
-    MOZ_ASSERT(aCompositionEvent->mMessage != NS_COMPOSITION_START);
+    MOZ_ASSERT(aCompositionEvent->mMessage != eCompositionStart);
   }
 #endif // #ifdef DEBUG
 
@@ -1277,7 +1277,7 @@ IMEStateManager::OnCompositionEventDiscarded(
 
   // Ignore compositionstart for now because sTextCompositions may not have
   // been created yet.
-  if (aCompositionEvent->mMessage == NS_COMPOSITION_START) {
+  if (aCompositionEvent->mMessage == eCompositionStart) {
     return;
   }
 
diff --git a/dom/events/TextComposition.cpp b/dom/events/TextComposition.cpp
index 79458fd5e5..b8c3d8d757 100644
--- a/dom/events/TextComposition.cpp
+++ b/dom/events/TextComposition.cpp
@@ -93,7 +93,7 @@ TextComposition::MaybeDispatchCompositionUpdate(
   if (mLastData == aCompositionEvent->mData) {
     return true;
   }
-  CloneAndDispatchAs(aCompositionEvent, NS_COMPOSITION_UPDATE);
+  CloneAndDispatchAs(aCompositionEvent, eCompositionUpdate);
   return IsValidStateForComposition(aCompositionEvent->widget);
 }
 
@@ -120,7 +120,7 @@ TextComposition::CloneAndDispatchAs(
 
   nsEventStatus dummyStatus = nsEventStatus_eConsumeNoDefault;
   nsEventStatus* status = aStatus ? aStatus : &dummyStatus;
-  if (aMessage == NS_COMPOSITION_UPDATE) {
+  if (aMessage == eCompositionUpdate) {
     mLastData = compositionEvent.mData;
   }
   EventDispatcher::Dispatch(mNode, mPresContext,
@@ -234,12 +234,12 @@ TextComposition::DispatchCompositionEvent(
     RemoveControlCharactersFrom(aCompositionEvent->mData,
                                 aCompositionEvent->mRanges);
   }
-  if (aCompositionEvent->mMessage == NS_COMPOSITION_COMMIT_AS_IS) {
+  if (aCompositionEvent->mMessage == eCompositionCommitAsIs) {
     NS_ASSERTION(!aCompositionEvent->mRanges,
-                 "mRanges of NS_COMPOSITION_COMMIT_AS_IS should be null");
+                 "mRanges of eCompositionCommitAsIs should be null");
     aCompositionEvent->mRanges = nullptr;
     NS_ASSERTION(aCompositionEvent->mData.IsEmpty(),
-                 "mData of NS_COMPOSITION_COMMIT_AS_IS should be empty string");
+                 "mData of eCompositionCommitAsIs should be empty string");
     if (mLastData == IDEOGRAPHIC_SPACE) {
       // If the last data is an ideographic space (FullWidth space), it must be
       // a placeholder character of some Chinese IME.  So, committing with
@@ -248,9 +248,9 @@ TextComposition::DispatchCompositionEvent(
     } else {
       aCompositionEvent->mData = mLastData;
     }
-  } else if (aCompositionEvent->mMessage == NS_COMPOSITION_COMMIT) {
+  } else if (aCompositionEvent->mMessage == eCompositionCommit) {
     NS_ASSERTION(!aCompositionEvent->mRanges,
-                 "mRanges of NS_COMPOSITION_COMMIT should be null");
+                 "mRanges of eCompositionCommit should be null");
     aCompositionEvent->mRanges = nullptr;
   }
 
@@ -284,10 +284,10 @@ TextComposition::DispatchCompositionEvent(
   if (!aIsSynthesized && (mIsRequestingCommit || mIsRequestingCancel)) {
     nsString* committingData = nullptr;
     switch (aCompositionEvent->mMessage) {
-      case NS_COMPOSITION_END:
-      case NS_COMPOSITION_CHANGE:
-      case NS_COMPOSITION_COMMIT_AS_IS:
-      case NS_COMPOSITION_COMMIT:
+      case eCompositionEnd:
+      case eCompositionChange:
+      case eCompositionCommitAsIs:
+      case eCompositionCommit:
         committingData = &aCompositionEvent->mData;
         break;
       default:
@@ -309,20 +309,20 @@ TextComposition::DispatchCompositionEvent(
   bool dispatchDOMTextEvent = aCompositionEvent->CausesDOMTextEvent();
 
   // When mIsComposing is false but the committing string is different from
-  // the last data (E.g., previous NS_COMPOSITION_CHANGE event made the
+  // the last data (E.g., previous eCompositionChange event made the
   // composition string empty or didn't have clause information), we don't
   // need to dispatch redundant DOM text event.
   if (dispatchDOMTextEvent &&
-      aCompositionEvent->mMessage != NS_COMPOSITION_CHANGE &&
+      aCompositionEvent->mMessage != eCompositionChange &&
       !mIsComposing && mLastData == aCompositionEvent->mData) {
     dispatchEvent = dispatchDOMTextEvent = false;
   }
 
-  // widget may dispatch redundant NS_COMPOSITION_CHANGE event
+  // widget may dispatch redundant eCompositionChange event
   // which modifies neither composition string, clauses nor caret
   // position.  In such case, we shouldn't dispatch DOM events.
   if (dispatchDOMTextEvent &&
-      aCompositionEvent->mMessage == NS_COMPOSITION_CHANGE &&
+      aCompositionEvent->mMessage == eCompositionChange &&
       mLastData == aCompositionEvent->mData &&
       mRanges && aCompositionEvent->mRanges &&
       mRanges->Equals(*aCompositionEvent->mRanges)) {
@@ -337,13 +337,13 @@ TextComposition::DispatchCompositionEvent(
 
   if (dispatchEvent) {
     // If the composition event should cause a DOM text event, we should
-    // overwrite the event message as NS_COMPOSITION_CHANGE because due to
+    // overwrite the event message as eCompositionChange because due to
     // the limitation of mapping between event messages and DOM event types,
     // we cannot map multiple event messages to a DOM event type.
     if (dispatchDOMTextEvent &&
-        aCompositionEvent->mMessage != NS_COMPOSITION_CHANGE) {
+        aCompositionEvent->mMessage != eCompositionChange) {
       aCompositionEvent->mFlags =
-        CloneAndDispatchAs(aCompositionEvent, NS_COMPOSITION_CHANGE,
+        CloneAndDispatchAs(aCompositionEvent, eCompositionChange,
                            aStatus, aCallBack);
     } else {
       EventDispatcher::Dispatch(mNode, mPresContext,
@@ -366,8 +366,8 @@ TextComposition::DispatchCompositionEvent(
 
   if (aCompositionEvent->CausesDOMCompositionEndEvent()) {
     // Dispatch a compositionend event if it's necessary.
-    if (aCompositionEvent->mMessage != NS_COMPOSITION_END) {
-      CloneAndDispatchAs(aCompositionEvent, NS_COMPOSITION_END);
+    if (aCompositionEvent->mMessage != eCompositionEnd) {
+      CloneAndDispatchAs(aCompositionEvent, eCompositionEnd);
     }
     MOZ_ASSERT(!mIsComposing, "Why is the editor still composing?");
     MOZ_ASSERT(!HasEditor(), "Why does the editor still keep to hold this?");
@@ -412,7 +412,7 @@ TextComposition::NotityUpdateComposition(
   // When compositon start, notify the rect of first offset character.
   // When not compositon start, notify the rect of selected composition
   // string if compositionchange event.
-  if (aCompositionEvent->mMessage == NS_COMPOSITION_START) {
+  if (aCompositionEvent->mMessage == eCompositionStart) {
     nsCOMPtr<nsIWidget> widget = mPresContext->GetRootWidget();
     // Update composition start offset
     WidgetQueryContentEvent selectedTextEvent(true, eQuerySelectedText, widget);
@@ -490,10 +490,10 @@ TextComposition::RequestToCommit(nsIWidget* aWidget, bool aDiscard)
   // Otherwise, synthesize the commit in content.
   nsAutoString data(aDiscard ? EmptyString() : lastData);
   if (data == mLastData) {
-    DispatchCompositionEventRunnable(NS_COMPOSITION_COMMIT_AS_IS, EmptyString(),
+    DispatchCompositionEventRunnable(eCompositionCommitAsIs, EmptyString(),
                                      true);
   } else {
-    DispatchCompositionEventRunnable(NS_COMPOSITION_COMMIT, data, true);
+    DispatchCompositionEventRunnable(eCompositionCommit, data, true);
   }
   return NS_OK;
 }
@@ -611,8 +611,8 @@ TextComposition::CompositionEventDispatcher::Run()
   nsRefPtr<nsPresContext> presContext = mTextComposition->mPresContext;
   nsEventStatus status = nsEventStatus_eIgnore;
   switch (mEventMessage) {
-    case NS_COMPOSITION_START: {
-      WidgetCompositionEvent compStart(true, NS_COMPOSITION_START, widget);
+    case eCompositionStart: {
+      WidgetCompositionEvent compStart(true, eCompositionStart, widget);
       WidgetQueryContentEvent selectedText(true, eQuerySelectedText, widget);
       ContentEventHandler handler(presContext);
       handler.OnQuerySelectedText(&selectedText);
@@ -625,11 +625,11 @@ TextComposition::CompositionEventDispatcher::Run()
                                                 mIsSynthesizedEvent);
       break;
     }
-    case NS_COMPOSITION_CHANGE:
-    case NS_COMPOSITION_COMMIT_AS_IS:
-    case NS_COMPOSITION_COMMIT: {
+    case eCompositionChange:
+    case eCompositionCommitAsIs:
+    case eCompositionCommit: {
       WidgetCompositionEvent compEvent(true, mEventMessage, widget);
-      if (mEventMessage != NS_COMPOSITION_COMMIT_AS_IS) {
+      if (mEventMessage != eCompositionCommitAsIs) {
         compEvent.mData = mData;
       }
       compEvent.mFlags.mIsSynthesizedForTests =
diff --git a/dom/events/WheelHandlingHelper.cpp b/dom/events/WheelHandlingHelper.cpp
index 79bb04503e..136fdf8583 100644
--- a/dom/events/WheelHandlingHelper.cpp
+++ b/dom/events/WheelHandlingHelper.cpp
@@ -94,7 +94,7 @@ WheelTransaction::BeginTransaction(nsIFrame* aTargetFrame,
                                    WidgetWheelEvent* aEvent)
 {
   NS_ASSERTION(!sTargetFrame, "previous transaction is not finished!");
-  MOZ_ASSERT(aEvent->mMessage == NS_WHEEL_WHEEL,
+  MOZ_ASSERT(aEvent->mMessage == eWheel,
              "Transaction must be started with a wheel event");
   ScrollbarsForWheel::OwnWheelTransaction(false);
   sTargetFrame = aTargetFrame;
@@ -176,7 +176,7 @@ WheelTransaction::OnEvent(WidgetEvent* aEvent)
   }
 
   switch (aEvent->mMessage) {
-    case NS_WHEEL_WHEEL:
+    case eWheel:
       if (sMouseMoved != 0 &&
           OutOfTime(sMouseMoved, GetIgnoreMoveDelayTime())) {
         // Terminate the current mousewheel transaction if the mouse moved more
@@ -415,7 +415,7 @@ ScrollbarsForWheel::PrepareToScrollText(EventStateManager* aESM,
                                         nsIFrame* aTargetFrame,
                                         WidgetWheelEvent* aEvent)
 {
-  if (aEvent->mMessage == NS_WHEEL_START) {
+  if (aEvent->mMessage == eWheelOperationStart) {
     WheelTransaction::OwnScrollbars(false);
     if (!IsActive()) {
       TemporarilyActivateAllPossibleScrollTargets(aESM, aTargetFrame, aEvent);
diff --git a/dom/events/WheelHandlingHelper.h b/dom/events/WheelHandlingHelper.h
index 115cb89e42..4b37eb0434 100644
--- a/dom/events/WheelHandlingHelper.h
+++ b/dom/events/WheelHandlingHelper.h
@@ -95,8 +95,8 @@ protected:
 
 
   /**
-   * These two methods are called upon NS_WHEEL_START/NS_WHEEL_STOP events
-   * to show/hide the right scrollbars.
+   * These two methods are called upon eWheelOperationStart/eWheelOperationEnd
+   * events to show/hide the right scrollbars.
    */
   static void TemporarilyActivateAllPossibleScrollTargets(
                 EventStateManager* aESM,
diff --git a/dom/html/HTMLInputElement.cpp b/dom/html/HTMLInputElement.cpp
index 245307b1c3..b2ca1b024d 100644
--- a/dom/html/HTMLInputElement.cpp
+++ b/dom/html/HTMLInputElement.cpp
@@ -3023,8 +3023,8 @@ HTMLInputElement::NeedToInitializeEditorForEvent(
   case eMouseExitFromWidget:
   case eMouseOver:
   case eMouseOut:
-  case NS_SCROLLPORT_UNDERFLOW:
-  case NS_SCROLLPORT_OVERFLOW:
+  case eScrollPortUnderflow:
+  case eScrollPortOverflow:
     return false;
   default:
     return true;
diff --git a/dom/html/nsGenericHTMLElement.cpp b/dom/html/nsGenericHTMLElement.cpp
index 5e7d8a1165..88dfac1a80 100644
--- a/dom/html/nsGenericHTMLElement.cpp
+++ b/dom/html/nsGenericHTMLElement.cpp
@@ -2457,7 +2457,7 @@ nsGenericHTMLFormElement::IsElementDisabledForEvents(EventMessage aMessage,
     case ePointerOut:
     case ePointerEnter:
     case ePointerLeave:
-    case NS_WHEEL_WHEEL:
+    case eWheel:
     case eLegacyMouseLineOrPageScroll:
     case eLegacyMousePixelScroll:
       return false;
diff --git a/dom/ipc/TabParent.cpp b/dom/ipc/TabParent.cpp
index 432cca970c..c53d58952e 100644
--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -2333,7 +2333,7 @@ TabParent::HandleQueryContentEvent(WidgetQueryContentEvent& aEvent)
     return true;
   }
   switch (aEvent.mMessage) {
-    case NS_QUERY_TEXT_RECT:
+    case eQueryTextRect:
     case eQueryCaretRect:
     case eQueryEditorRect:
       aEvent.mReply.mRect -= GetChildProcessOffset();
diff --git a/dom/smil/nsSMILTimedElement.cpp b/dom/smil/nsSMILTimedElement.cpp
index 2858c21e08..082a5f906c 100644
--- a/dom/smil/nsSMILTimedElement.cpp
+++ b/dom/smil/nsSMILTimedElement.cpp
@@ -643,7 +643,7 @@ nsSMILTimedElement::DoSampleAt(nsSMILTime aContainerTime, bool aEndOnly)
             mClient->Activate(mCurrentInterval->Begin()->Time().GetMillis());
           }
           if (mSeekState == SEEK_NOT_SEEKING) {
-            FireTimeEventAsync(NS_SMIL_BEGIN, 0);
+            FireTimeEventAsync(eSMILBeginEvent, 0);
           }
           if (HasPlayed()) {
             Reset(); // Apply restart behaviour
@@ -679,7 +679,7 @@ nsSMILTimedElement::DoSampleAt(nsSMILTime aContainerTime, bool aEndOnly)
           }
           mCurrentInterval->FixEnd();
           if (mSeekState == SEEK_NOT_SEEKING) {
-            FireTimeEventAsync(NS_SMIL_END, 0);
+            FireTimeEventAsync(eSMILEndEvent, 0);
           }
           mCurrentRepeatIteration = 0;
           mOldIntervals.AppendElement(mCurrentInterval.forget());
@@ -727,7 +727,7 @@ nsSMILTimedElement::DoSampleAt(nsSMILTime aContainerTime, bool aEndOnly)
               mCurrentRepeatIteration != prevRepeatIteration &&
               mCurrentRepeatIteration &&
               mSeekState == SEEK_NOT_SEEKING) {
-              FireTimeEventAsync(NS_SMIL_REPEAT,
+              FireTimeEventAsync(eSMILRepeatEvent,
                             static_cast<int32_t>(mCurrentRepeatIteration));
             }
           }
@@ -1518,14 +1518,14 @@ nsSMILTimedElement::DoPostSeek()
   case SEEK_FORWARD_FROM_ACTIVE:
   case SEEK_BACKWARD_FROM_ACTIVE:
     if (mElementState != STATE_ACTIVE) {
-      FireTimeEventAsync(NS_SMIL_END, 0);
+      FireTimeEventAsync(eSMILEndEvent, 0);
     }
     break;
 
   case SEEK_FORWARD_FROM_INACTIVE:
   case SEEK_BACKWARD_FROM_INACTIVE:
     if (mElementState == STATE_ACTIVE) {
-      FireTimeEventAsync(NS_SMIL_BEGIN, 0);
+      FireTimeEventAsync(eSMILBeginEvent, 0);
     }
     break;
 
diff --git a/editor/libeditor/nsEditor.cpp b/editor/libeditor/nsEditor.cpp
index 7abebd5113..01e71e3736 100644
--- a/editor/libeditor/nsEditor.cpp
+++ b/editor/libeditor/nsEditor.cpp
@@ -261,7 +261,7 @@ nsEditor::Init(nsIDOMDocument *aDoc, nsIContent *aRoot,
   // recreated with same content. Therefore, we need to forget mIMETextNode,
   // but we need to keep storing mIMETextOffset and mIMETextLength becuase
   // they are necessary to restore IME selection and replacing composing string
-  // when this receives NS_COMPOSITION_CHANGE event next time.
+  // when this receives eCompositionChange event next time.
   if (mIMETextNode && !mIMETextNode->IsInComposedDoc()) {
     mIMETextNode = nullptr;
   }
@@ -5126,11 +5126,11 @@ nsEditor::IsAcceptableInputEvent(nsIDOMEvent* aEvent)
       // If events are not created with proper event interface, their message
       // are initialized with eUnidentifiedEvent.  Let's ignore such event.
       return false;
-    case NS_COMPOSITION_START:
-    case NS_COMPOSITION_END:
-    case NS_COMPOSITION_UPDATE:
-    case NS_COMPOSITION_CHANGE:
-    case NS_COMPOSITION_COMMIT_AS_IS:
+    case eCompositionStart:
+    case eCompositionEnd:
+    case eCompositionUpdate:
+    case eCompositionChange:
+    case eCompositionCommitAsIs:
       // Don't allow composition events whose internal event are not
       // WidgetCompositionEvent.
       widgetGUIEvent = aEvent->GetInternalNSEvent()->AsCompositionEvent();
diff --git a/editor/libeditor/nsEditorEventListener.cpp b/editor/libeditor/nsEditorEventListener.cpp
index 470a5db7de..433cd1b237 100644
--- a/editor/libeditor/nsEditorEventListener.cpp
+++ b/editor/libeditor/nsEditorEventListener.cpp
@@ -460,13 +460,13 @@ nsEditorEventListener::HandleEvent(nsIDOMEvent* aEvent)
     case eBlur:
       return Blur(aEvent);
     // text
-    case NS_COMPOSITION_CHANGE:
+    case eCompositionChange:
       return HandleText(aEvent);
     // compositionstart
-    case NS_COMPOSITION_START:
+    case eCompositionStart:
       return HandleStartComposition(aEvent);
     // compositionend
-    case NS_COMPOSITION_END:
+    case eCompositionEnd:
       HandleEndComposition(aEvent);
       return NS_OK;
     default:
diff --git a/editor/libeditor/nsPlaintextEditor.cpp b/editor/libeditor/nsPlaintextEditor.cpp
index c3e5ce13a3..67df3e24a4 100644
--- a/editor/libeditor/nsPlaintextEditor.cpp
+++ b/editor/libeditor/nsPlaintextEditor.cpp
@@ -845,8 +845,8 @@ nsPlaintextEditor::UpdateIMEComposition(nsIDOMEvent* aDOMTextEvent)
   WidgetCompositionEvent* compositionChangeEvent =
     aDOMTextEvent->GetInternalNSEvent()->AsCompositionEvent();
   NS_ENSURE_TRUE(compositionChangeEvent, NS_ERROR_INVALID_ARG);
-  MOZ_ASSERT(compositionChangeEvent->mMessage == NS_COMPOSITION_CHANGE,
-             "The internal event should be NS_COMPOSITION_CHANGE");
+  MOZ_ASSERT(compositionChangeEvent->mMessage == eCompositionChange,
+             "The internal event should be eCompositionChange");
 
   EnsureComposition(compositionChangeEvent);
 
diff --git a/layout/base/AccessibleCaretEventHub.cpp b/layout/base/AccessibleCaretEventHub.cpp
index 6fd3576d87..c0f908b2f6 100644
--- a/layout/base/AccessibleCaretEventHub.cpp
+++ b/layout/base/AccessibleCaretEventHub.cpp
@@ -534,19 +534,19 @@ nsEventStatus
 AccessibleCaretEventHub::HandleWheelEvent(WidgetWheelEvent* aEvent)
 {
   switch (aEvent->mMessage) {
-  case NS_WHEEL_WHEEL:
-    AC_LOGV("NS_WHEEL_WHEEL, isMomentum %d, state: %s", aEvent->isMomentum,
+  case eWheel:
+    AC_LOGV("eWheel, isMomentum %d, state: %s", aEvent->isMomentum,
             mState->Name());
     mState->OnScrolling(this);
     break;
 
-  case NS_WHEEL_START:
-    AC_LOGV("NS_WHEEL_START, state: %s", mState->Name());
+  case eWheelOperationStart:
+    AC_LOGV("eWheelOperationStart, state: %s", mState->Name());
     mState->OnScrollStart(this);
     break;
 
-  case NS_WHEEL_STOP:
-    AC_LOGV("NS_WHEEL_STOP, state: %s", mState->Name());
+  case eWheelOperationEnd:
+    AC_LOGV("eWheelOperationEnd, state: %s", mState->Name());
     mState->OnScrollEnd(this);
     break;
 
diff --git a/layout/base/TouchCaret.cpp b/layout/base/TouchCaret.cpp
index fca14eb105..c180963b08 100644
--- a/layout/base/TouchCaret.cpp
+++ b/layout/base/TouchCaret.cpp
@@ -788,9 +788,9 @@ TouchCaret::HandleEvent(WidgetEvent* aEvent)
     case eKeyUp:
     case eKeyDown:
     case eKeyPress:
-    case NS_WHEEL_WHEEL:
-    case NS_WHEEL_START:
-    case NS_WHEEL_STOP:
+    case eWheel:
+    case eWheelOperationStart:
+    case eWheelOperationEnd:
       // Disable touch caret while key/wheel event is received.
       TOUCHCARET_LOG("Receive key/wheel event %d", aEvent->mMessage);
       SetVisibility(false);
diff --git a/layout/base/gtest/TestAccessibleCaretEventHub.cpp b/layout/base/gtest/TestAccessibleCaretEventHub.cpp
index 39866a64c6..25fbdacd2b 100644
--- a/layout/base/gtest/TestAccessibleCaretEventHub.cpp
+++ b/layout/base/gtest/TestAccessibleCaretEventHub.cpp
@@ -732,22 +732,22 @@ TEST_F(AccessibleCaretEventHubTester, TestWheelEventScroll)
 
   check.Call("1");
 
-  HandleEventAndCheckState(CreateWheelEvent(NS_WHEEL_START),
+  HandleEventAndCheckState(CreateWheelEvent(eWheelOperationStart),
                            MockAccessibleCaretEventHub::ScrollState(),
                            nsEventStatus_eIgnore);
 
-  HandleEventAndCheckState(CreateWheelEvent(NS_WHEEL_WHEEL),
+  HandleEventAndCheckState(CreateWheelEvent(eWheel),
                            MockAccessibleCaretEventHub::ScrollState(),
                            nsEventStatus_eIgnore);
 
   mHub->ScrollPositionChanged();
 
-  HandleEventAndCheckState(CreateWheelEvent(NS_WHEEL_STOP),
+  HandleEventAndCheckState(CreateWheelEvent(eWheelOperationEnd),
                            MockAccessibleCaretEventHub::PostScrollState(),
                            nsEventStatus_eIgnore);
 
   // Momentum scroll
-  HandleEventAndCheckState(CreateWheelEvent(NS_WHEEL_WHEEL),
+  HandleEventAndCheckState(CreateWheelEvent(eWheel),
                            MockAccessibleCaretEventHub::PostScrollState(),
                            nsEventStatus_eIgnore);
 
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index e074b04b1f..e430cbe79a 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -476,7 +476,7 @@ public:
         // will return a real frame and we don't have to worry about
         // destroying it by flushing later.
         mPresShell->FlushPendingNotifications(Flush_Layout);
-      } else if (aVisitor.mEvent->mMessage == NS_WHEEL_WHEEL &&
+      } else if (aVisitor.mEvent->mMessage == eWheel &&
                  aVisitor.mEventStatus != nsEventStatus_eConsumeNoDefault) {
         nsIFrame* frame = mPresShell->GetCurrentEventFrame();
         if (frame) {
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index eebfda50ae..3dd377f47f 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -3731,7 +3731,7 @@ ScrollFrameHelper::FireScrollPortEvent()
   InternalScrollPortEvent event(true,
     (orient == InternalScrollPortEvent::horizontal ? mHorizontalOverflow :
                                                      mVerticalOverflow) ?
-    NS_SCROLLPORT_OVERFLOW : NS_SCROLLPORT_UNDERFLOW, nullptr);
+    eScrollPortOverflow : eScrollPortUnderflow, nullptr);
   event.orient = orient;
   return EventDispatcher::Dispatch(mOuter->GetContent(),
                                    mOuter->PresContext(), &event);
@@ -5280,7 +5280,7 @@ ScrollFrameHelper::FireScrolledAreaEvent()
 {
   mScrolledAreaEvent.Forget();
 
-  InternalScrollAreaEvent event(true, NS_SCROLLEDAREACHANGED, nullptr);
+  InternalScrollAreaEvent event(true, eScrolledAreaChanged, nullptr);
   nsPresContext *prescontext = mOuter->PresContext();
   nsIContent* content = mOuter->GetContent();
 
diff --git a/layout/generic/nsPluginFrame.cpp b/layout/generic/nsPluginFrame.cpp
index 0a48191f22..1efb624eea 100644
--- a/layout/generic/nsPluginFrame.cpp
+++ b/layout/generic/nsPluginFrame.cpp
@@ -1787,7 +1787,7 @@ nsPluginFrame::HandleEvent(nsPresContext* aPresContext,
 #ifdef XP_MACOSX
   // we want to process some native mouse events in the cocoa event model
   if ((anEvent->mMessage == eMouseEnterIntoWidget ||
-       anEvent->mMessage == NS_WHEEL_WHEEL) &&
+       anEvent->mMessage == eWheel) &&
       mInstanceOwner->GetEventModel() == NPEventModelCocoa) {
     *anEventStatus = mInstanceOwner->ProcessEvent(*anEvent);
     // Due to plugin code reentering Gecko, this frame may be dead at this
diff --git a/layout/xul/tree/nsTreeBodyFrame.cpp b/layout/xul/tree/nsTreeBodyFrame.cpp
index 60985a4e3d..31f4ac8616 100644
--- a/layout/xul/tree/nsTreeBodyFrame.cpp
+++ b/layout/xul/tree/nsTreeBodyFrame.cpp
@@ -918,7 +918,7 @@ nsTreeBodyFrame::CheckOverflow(const ScrollParts& aParts)
 
   if (verticalOverflowChanged) {
     InternalScrollPortEvent event(true,
-      mVerticalOverflow ? NS_SCROLLPORT_OVERFLOW : NS_SCROLLPORT_UNDERFLOW,
+      mVerticalOverflow ? eScrollPortOverflow : eScrollPortUnderflow,
       nullptr);
     event.orient = InternalScrollPortEvent::vertical;
     EventDispatcher::Dispatch(content, presContext, &event);
@@ -926,7 +926,7 @@ nsTreeBodyFrame::CheckOverflow(const ScrollParts& aParts)
 
   if (horizontalOverflowChanged) {
     InternalScrollPortEvent event(true,
-      mHorizontalOverflow ? NS_SCROLLPORT_OVERFLOW : NS_SCROLLPORT_UNDERFLOW,
+      mHorizontalOverflow ? eScrollPortOverflow : eScrollPortUnderflow,
       nullptr);
     event.orient = InternalScrollPortEvent::horizontal;
     EventDispatcher::Dispatch(content, presContext, &event);
diff --git a/widget/ContentCache.cpp b/widget/ContentCache.cpp
index efe4844293..dda11aae88 100644
--- a/widget/ContentCache.cpp
+++ b/widget/ContentCache.cpp
@@ -27,18 +27,18 @@ static const char*
 GetEventMessageName(EventMessage aMessage)
 {
   switch (aMessage) {
-    case NS_COMPOSITION_START:
-      return "NS_COMPOSITION_START";
-    case NS_COMPOSITION_END:
-      return "NS_COMPOSITION_END";
-    case NS_COMPOSITION_UPDATE:
-      return "NS_COMPOSITION_UPDATE";
-    case NS_COMPOSITION_CHANGE:
-      return "NS_COMPOSITION_CHANGE";
-    case NS_COMPOSITION_COMMIT_AS_IS:
-      return "NS_COMPOSITION_COMMIT_AS_IS";
-    case NS_COMPOSITION_COMMIT:
-      return "NS_COMPOSITION_COMMIT";
+    case eCompositionStart:
+      return "eCompositionStart";
+    case eCompositionEnd:
+      return "eCompositionEnd";
+    case eCompositionUpdate:
+      return "eCompositionUpdate";
+    case eCompositionChange:
+      return "eCompositionChange";
+    case eCompositionCommitAsIs:
+      return "eCompositionCommitAsIs";
+    case eCompositionCommit:
+      return "eCompositionCommit";
     case eSetSelection:
       return "eSetSelection";
     default:
@@ -302,7 +302,7 @@ ContentCacheInChild::QueryCharRect(nsIWidget* aWidget,
   aCharRect.SetEmpty();
 
   nsEventStatus status = nsEventStatus_eIgnore;
-  WidgetQueryContentEvent textRect(true, NS_QUERY_TEXT_RECT, aWidget);
+  WidgetQueryContentEvent textRect(true, eQueryTextRect, aWidget);
   textRect.InitForQueryTextRect(aOffset, 1);
   aWidget->DispatchEvent(&textRect, status);
   if (NS_WARN_IF(!textRect.mSucceeded)) {
@@ -394,7 +394,7 @@ ContentCacheInChild::CacheTextRects(nsIWidget* aWidget,
 
   if (!mSelection.Collapsed()) {
     nsEventStatus status = nsEventStatus_eIgnore;
-    WidgetQueryContentEvent textRect(true, NS_QUERY_TEXT_RECT, aWidget);
+    WidgetQueryContentEvent textRect(true, eQueryTextRect, aWidget);
     textRect.InitForQueryTextRect(mSelection.StartOffset(),
                                   mSelection.Length());
     aWidget->DispatchEvent(&textRect, status);
@@ -583,10 +583,10 @@ ContentCacheInParent::HandleQueryContentEvent(WidgetQueryContentEvent& aEvent,
          this, aEvent.mReply.mOffset, aEvent.mReply.mString.Length()));
       break;
     }
-    case NS_QUERY_TEXT_RECT:
+    case eQueryTextRect:
       MOZ_LOG(sContentCacheLog, LogLevel::Info,
         ("ContentCacheInParent: 0x%p HandleQueryContentEvent("
-         "aEvent={ mMessage=NS_QUERY_TEXT_RECT, mInput={ mOffset=%u, "
+         "aEvent={ mMessage=eQueryTextRect, mInput={ mOffset=%u, "
          "mLength=%u } }, aWidget=0x%p), mText.Length()=%u",
          this, aEvent.mInput.mOffset, aEvent.mInput.mLength, aWidget,
          mText.Length()));
@@ -858,7 +858,7 @@ ContentCacheInParent::OnCompositionEvent(const WidgetCompositionEvent& aEvent)
      GetBoolName(mRequestedToCommitOrCancelComposition)));
 
   if (!aEvent.CausesDOMTextEvent()) {
-    MOZ_ASSERT(aEvent.mMessage == NS_COMPOSITION_START);
+    MOZ_ASSERT(aEvent.mMessage == eCompositionStart);
     mIsComposing = !aEvent.CausesDOMCompositionEndEvent();
     mCompositionStart = mSelection.StartOffset();
     // XXX What's this case??
@@ -875,7 +875,7 @@ ContentCacheInParent::OnCompositionEvent(const WidgetCompositionEvent& aEvent)
   //     TextComposition must handle following events correctly!
 
   // During REQUEST_TO_COMMIT_COMPOSITION or REQUEST_TO_CANCEL_COMPOSITION,
-  // widget usually sends a NS_COMPOSITION_CHANGE event to finalize or
+  // widget usually sends a eCompositionChange event to finalize or
   // clear the composition, respectively.
   // Because the event will not reach content in time, we intercept it
   // here and pass the text as the DidRequestToCommitOrCancelComposition()
diff --git a/widget/ContentCache.h b/widget/ContentCache.h
index 29070708c1..96bc3f64e9 100644
--- a/widget/ContentCache.h
+++ b/widget/ContentCache.h
@@ -293,7 +293,7 @@ public:
    *  knowing the exact length of text. It's up to widget to handle cases when
    *  the returned offset/length are different from the queried offset/length.
    *
-   * For NS_QUERY_TEXT_RECT, fail if cached offset/length aren't equals to input.
+   * For eQueryTextRect, fail if cached offset/length aren't equals to input.
    *   Cocoa widget always queries selected offset, so it works on it.
    *
    * For eQueryCaretRect, fail if cached offset isn't equals to input
diff --git a/widget/EventMessageList.h b/widget/EventMessageList.h
index e28fc76b0e..bb63f3769b 100644
--- a/widget/EventMessageList.h
+++ b/widget/EventMessageList.h
@@ -128,9 +128,9 @@ NS_EVENT_MESSAGE(eLegacyMouseScrollEventFirst, 1600)
 NS_EVENT_MESSAGE(eLegacyMouseLineOrPageScroll, eLegacyMouseScrollEventFirst)
 NS_EVENT_MESSAGE(eLegacyMousePixelScroll,      eLegacyMouseScrollEventFirst + 1)
 
-NS_EVENT_MESSAGE(NS_SCROLLPORT_START,     1700)
-NS_EVENT_MESSAGE(NS_SCROLLPORT_UNDERFLOW, NS_SCROLLPORT_START)
-NS_EVENT_MESSAGE(NS_SCROLLPORT_OVERFLOW,  NS_SCROLLPORT_START + 1)
+NS_EVENT_MESSAGE(eScrollPortEventFirst, 1700)
+NS_EVENT_MESSAGE(eScrollPortUnderflow,  eScrollPortEventFirst)
+NS_EVENT_MESSAGE(eScrollPortOverflow,   eScrollPortEventFirst + 1)
 
 NS_EVENT_MESSAGE(eLegacyMutationEventFirst,       1800)
 NS_EVENT_MESSAGE(eLegacySubtreeModified,          eLegacyMutationEventFirst)
@@ -145,35 +145,35 @@ NS_EVENT_MESSAGE(eLegacyMutationEventLast,        eLegacyCharacterDataModified)
 NS_EVENT_MESSAGE(eUnidentifiedEvent,    2000)
  
 // composition events
-NS_EVENT_MESSAGE(NS_COMPOSITION_EVENT_START,  2200)
-NS_EVENT_MESSAGE(NS_COMPOSITION_START,        NS_COMPOSITION_EVENT_START)
-// NS_COMPOSITION_END is the message for DOM compositionend event.
-// This event should NOT be dispatched from widget if NS_COMPOSITION_COMMIT
+NS_EVENT_MESSAGE(eCompositionEventFirst, 2200)
+NS_EVENT_MESSAGE(eCompositionStart,      eCompositionEventFirst)
+// eCompositionEnd is the message for DOM compositionend event.
+// This event should NOT be dispatched from widget if eCompositionCommit
 // is available.
-NS_EVENT_MESSAGE(NS_COMPOSITION_END,          NS_COMPOSITION_EVENT_START + 1)
-// NS_COMPOSITION_UPDATE is the message for DOM compositionupdate event.
+NS_EVENT_MESSAGE(eCompositionEnd,        eCompositionEventFirst + 1)
+// eCompositionUpdate is the message for DOM compositionupdate event.
 // This event should NOT be dispatched from widget since it will be dispatched
-// by mozilla::TextComposition automatically if NS_COMPOSITION_CHANGE event
+// by mozilla::TextComposition automatically if eCompositionChange event
 // will change composition string.
-NS_EVENT_MESSAGE(NS_COMPOSITION_UPDATE,       NS_COMPOSITION_EVENT_START + 2)
-// NS_COMPOSITION_CHANGE is the message for representing a change of
+NS_EVENT_MESSAGE(eCompositionUpdate,     eCompositionEventFirst + 2)
+// eCompositionChange is the message for representing a change of
 // composition string.  This should be dispatched from widget even if
 // composition string isn't changed but the ranges are changed.  This causes
 // a DOM "text" event which is a non-standard DOM event.
-NS_EVENT_MESSAGE(NS_COMPOSITION_CHANGE,       NS_COMPOSITION_EVENT_START + 3)
-// NS_COMPOSITION_COMMIT_AS_IS is the message for representing a commit of
+NS_EVENT_MESSAGE(eCompositionChange,     eCompositionEventFirst + 3)
+// eCompositionCommitAsIs is the message for representing a commit of
 // composition string.  TextComposition will commit composition with the
 // last data.  TextComposition will dispatch this event to the DOM tree as
-// NS_COMPOSITION_CHANGE without clause information.  After that,
-// NS_COMPOSITION_END will be dispatched automatically.
+// eCompositionChange without clause information.  After that,
+// eCompositionEnd will be dispatched automatically.
 // Its mData and mRanges should be empty and nullptr.
-NS_EVENT_MESSAGE(NS_COMPOSITION_COMMIT_AS_IS, NS_COMPOSITION_EVENT_START + 4)
-// NS_COMPOSITION_COMMIT is the message for representing a commit of
+NS_EVENT_MESSAGE(eCompositionCommitAsIs, eCompositionEventFirst + 4)
+// eCompositionCommit is the message for representing a commit of
 // composition string with its mData value.  TextComposition will dispatch this
-// event to the DOM tree as NS_COMPOSITION_CHANGE without clause information.
-// After that, NS_COMPOSITION_END will be dispatched automatically.
+// event to the DOM tree as eCompositionChange without clause information.
+// After that, eCompositionEnd will be dispatched automatically.
 // Its mRanges should be nullptr.
-NS_EVENT_MESSAGE(NS_COMPOSITION_COMMIT,       NS_COMPOSITION_EVENT_START + 5)
+NS_EVENT_MESSAGE(eCompositionCommit,     eCompositionEventFirst + 5)
 
 // Following events are defined for deprecated DOM events which are using
 // InternalUIEvent class.
@@ -226,7 +226,7 @@ NS_EVENT_MESSAGE(eQueryCaretRect,               eQueryContentEventFirst + 3)
 // Query for the bounding rect of a range of characters. This works on any
 // valid character range given offset and length. Result is relative to top
 // level widget coordinates
-NS_EVENT_MESSAGE(NS_QUERY_TEXT_RECT,            eQueryContentEventFirst + 4)
+NS_EVENT_MESSAGE(eQueryTextRect,                eQueryContentEventFirst + 4)
 // Query for the bounding rect of the current focused frame. Result is relative
 // to top level widget coordinates
 NS_EVENT_MESSAGE(eQueryEditorRect,              eQueryContentEventFirst + 5)
@@ -315,12 +315,10 @@ NS_EVENT_MESSAGE(eContentCommandPasteTransferable, eContentCommandEventFirst + 6
 NS_EVENT_MESSAGE(eContentCommandScroll,            eContentCommandEventFirst + 7)
 
 // Event to gesture notification
-NS_EVENT_MESSAGE(NS_GESTURENOTIFY_EVENT_START, 3900)
+NS_EVENT_MESSAGE(eGestureNotify,        3900)
 
-NS_EVENT_MESSAGE(NS_ORIENTATION_EVENT,  4000)
-
-NS_EVENT_MESSAGE(NS_SCROLLAREA_EVENT_START, 4100)
-NS_EVENT_MESSAGE(NS_SCROLLEDAREACHANGED, NS_SCROLLAREA_EVENT_START)
+NS_EVENT_MESSAGE(eScrolledAreaEventFirst, 4100)
+NS_EVENT_MESSAGE(eScrolledAreaChanged,    eScrolledAreaEventFirst)
 
 NS_EVENT_MESSAGE(NS_TRANSITION_EVENT_START, 4200)
 NS_EVENT_MESSAGE(NS_TRANSITION_END,     NS_TRANSITION_EVENT_START)
@@ -330,10 +328,10 @@ NS_EVENT_MESSAGE(eAnimationStart,       eAnimationEventFirst)
 NS_EVENT_MESSAGE(eAnimationEnd,         eAnimationEventFirst + 1)
 NS_EVENT_MESSAGE(eAnimationIteration,   eAnimationEventFirst + 2)
 
-NS_EVENT_MESSAGE(NS_SMIL_TIME_EVENT_START, 4300)
-NS_EVENT_MESSAGE(NS_SMIL_BEGIN,         NS_SMIL_TIME_EVENT_START)
-NS_EVENT_MESSAGE(NS_SMIL_END,           NS_SMIL_TIME_EVENT_START + 1)
-NS_EVENT_MESSAGE(NS_SMIL_REPEAT,        NS_SMIL_TIME_EVENT_START + 2)
+NS_EVENT_MESSAGE(eSMILEventFirst,       4300)
+NS_EVENT_MESSAGE(eSMILBeginEvent,       eSMILEventFirst)
+NS_EVENT_MESSAGE(eSMILEndEvent,         eSMILEventFirst + 1)
+NS_EVENT_MESSAGE(eSMILRepeatEvent,      eSMILEventFirst + 2)
 
 NS_EVENT_MESSAGE(NS_WEBAUDIO_EVENT_START, 4350)
 NS_EVENT_MESSAGE(NS_AUDIO_PROCESS,      NS_WEBAUDIO_EVENT_START)
@@ -344,9 +342,9 @@ NS_EVENT_MESSAGE(eScriptEventFirst,     4500)
 NS_EVENT_MESSAGE(eBeforeScriptExecute,  eScriptEventFirst)
 NS_EVENT_MESSAGE(eAfterScriptExecute,   eScriptEventFirst + 1)
 
-NS_EVENT_MESSAGE(NS_PRINT_EVENT_START,  4600)
-NS_EVENT_MESSAGE(NS_BEFOREPRINT,        NS_PRINT_EVENT_START)
-NS_EVENT_MESSAGE(NS_AFTERPRINT,         NS_PRINT_EVENT_START + 1)
+NS_EVENT_MESSAGE(ePrintEventFirst,      4600)
+NS_EVENT_MESSAGE(eBeforePrint,          ePrintEventFirst)
+NS_EVENT_MESSAGE(eAfterPrint,           ePrintEventFirst + 1)
 
 NS_EVENT_MESSAGE(NS_MESSAGE_EVENT_START, 4700)
 NS_EVENT_MESSAGE(NS_MESSAGE,            NS_MESSAGE_EVENT_START)
@@ -356,12 +354,12 @@ NS_EVENT_MESSAGE(eOpenCloseEventFirst,  4800)
 NS_EVENT_MESSAGE(eOpen,                 eOpenCloseEventFirst)
 
 // Device motion and orientation
-NS_EVENT_MESSAGE(NS_DEVICE_ORIENTATION_START, 4900)
-NS_EVENT_MESSAGE(NS_DEVICE_ORIENTATION,  NS_DEVICE_ORIENTATION_START)
-NS_EVENT_MESSAGE(NS_DEVICE_MOTION,       NS_DEVICE_ORIENTATION_START + 1)
-NS_EVENT_MESSAGE(NS_DEVICE_PROXIMITY,    NS_DEVICE_ORIENTATION_START + 2)
-NS_EVENT_MESSAGE(NS_USER_PROXIMITY,      NS_DEVICE_ORIENTATION_START + 3)
-NS_EVENT_MESSAGE(NS_DEVICE_LIGHT,        NS_DEVICE_ORIENTATION_START + 4)
+NS_EVENT_MESSAGE(eDeviceEventFirst,      4900)
+NS_EVENT_MESSAGE(eDeviceOrientation,     eDeviceEventFirst)
+NS_EVENT_MESSAGE(eDeviceMotion,          eDeviceEventFirst + 1)
+NS_EVENT_MESSAGE(eDeviceProximity,       eDeviceEventFirst + 2)
+NS_EVENT_MESSAGE(eUserProximity,         eDeviceEventFirst + 3)
+NS_EVENT_MESSAGE(eDeviceLight,           eDeviceEventFirst + 4)
 
 NS_EVENT_MESSAGE(NS_SHOW_EVENT,          5000)
 
@@ -377,22 +375,29 @@ NS_EVENT_MESSAGE(NS_TOUCH_END,           NS_TOUCH_EVENT_START + 2)
 NS_EVENT_MESSAGE(NS_TOUCH_CANCEL,        NS_TOUCH_EVENT_START + 3)
 
 // Pointerlock DOM API
-NS_EVENT_MESSAGE(NS_POINTERLOCK_START,   5300)
-NS_EVENT_MESSAGE(NS_POINTERLOCKCHANGE,   NS_POINTERLOCK_START)
-NS_EVENT_MESSAGE(NS_POINTERLOCKERROR,    NS_POINTERLOCK_START + 1)
+NS_EVENT_MESSAGE(ePointerLockEventFirst, 5300)
+NS_EVENT_MESSAGE(ePointerLockChange,     ePointerLockEventFirst)
+NS_EVENT_MESSAGE(ePointerLockError,      ePointerLockEventFirst + 1)
 
 NS_EVENT_MESSAGE(eWheelEventFirst,       5400)
-NS_EVENT_MESSAGE(NS_WHEEL_WHEEL,         eWheelEventFirst)
-NS_EVENT_MESSAGE(NS_WHEEL_START,         eWheelEventFirst + 1)
-NS_EVENT_MESSAGE(NS_WHEEL_STOP,          eWheelEventFirst + 2)
+// eWheel is the event message of DOM wheel event.
+NS_EVENT_MESSAGE(eWheel,                 eWheelEventFirst)
+// eWheelOperationStart may be dispatched when user starts to operate mouse
+// wheel.  This won't be fired on some platforms which don't have corresponding
+// native event.
+NS_EVENT_MESSAGE(eWheelOperationStart,   eWheelEventFirst + 1)
+// eWheelOperationEnd may be dispatched when user ends or cancels operating
+// mouse wheel.  This won't be fired on some platforms which don't have
+// corresponding native event.
+NS_EVENT_MESSAGE(eWheelOperationEnd,     eWheelEventFirst + 2)
 
 //System time is changed
-NS_EVENT_MESSAGE(NS_MOZ_TIME_CHANGE_EVENT, 5500)
+NS_EVENT_MESSAGE(eTimeChange,            5500)
 
 // Network packet events.
-NS_EVENT_MESSAGE(NS_NETWORK_EVENT_START,    5600)
-NS_EVENT_MESSAGE(NS_NETWORK_UPLOAD_EVENT,   NS_NETWORK_EVENT_START + 1)
-NS_EVENT_MESSAGE(NS_NETWORK_DOWNLOAD_EVENT, NS_NETWORK_EVENT_START + 2)
+NS_EVENT_MESSAGE(eNetworkEventFirst,     5600)
+NS_EVENT_MESSAGE(eNetworkUpload,         eNetworkEventFirst + 1)
+NS_EVENT_MESSAGE(eNetworkDownload,       eNetworkEventFirst + 2)
 
 // MediaRecorder events.
 NS_EVENT_MESSAGE(NS_MEDIARECORDER_EVENT_START, 5700)
@@ -406,14 +411,13 @@ NS_EVENT_MESSAGE(NS_SPEAKERMANAGER_SPEAKERFORCEDCHANGE, NS_SPEAKERMANAGER_EVENT_
 
 #ifdef MOZ_GAMEPAD
 // Gamepad input events
-NS_EVENT_MESSAGE(NS_GAMEPAD_START,        6000)
-NS_EVENT_MESSAGE(NS_GAMEPAD_BUTTONDOWN,   NS_GAMEPAD_START)
-NS_EVENT_MESSAGE(NS_GAMEPAD_BUTTONUP,     NS_GAMEPAD_START + 1)
-NS_EVENT_MESSAGE(NS_GAMEPAD_AXISMOVE,     NS_GAMEPAD_START + 2)
-NS_EVENT_MESSAGE(NS_GAMEPAD_CONNECTED,    NS_GAMEPAD_START + 3)
-NS_EVENT_MESSAGE(NS_GAMEPAD_DISCONNECTED, NS_GAMEPAD_START + 4)
-// Keep this defined to the same value as the event above
-NS_EVENT_MESSAGE(NS_GAMEPAD_END,          NS_GAMEPAD_START + 4)
+NS_EVENT_MESSAGE(eGamepadEventFirst,     6000)
+NS_EVENT_MESSAGE(eGamepadButtonDown,     eGamepadEventFirst)
+NS_EVENT_MESSAGE(eGamepadButtonUp,       eGamepadEventFirst + 1)
+NS_EVENT_MESSAGE(eGamepadAxisMove,       eGamepadEventFirst + 2)
+NS_EVENT_MESSAGE(eGamepadConnected,      eGamepadEventFirst + 3)
+NS_EVENT_MESSAGE(eGamepadDisconnected,   eGamepadEventFirst + 4)
+NS_EVENT_MESSAGE(eGamepadEventLast,      eGamepadDisconnected)
 #endif
 
 // input and beforeinput events.
@@ -423,11 +427,11 @@ NS_EVENT_MESSAGE(NS_EDITOR_INPUT,         NS_EDITOR_EVENT_START)
 // Selection events
 NS_EVENT_MESSAGE(NS_SELECT_EVENT_START,   6200)
 NS_EVENT_MESSAGE(NS_SELECT_START,         NS_SELECT_EVENT_START)
-NS_EVENT_MESSAGE(NS_SELECTION_CHANGE,     NS_SELECT_EVENT_START + 1)
+NS_EVENT_MESSAGE(eSelectionChange,       NS_SELECT_EVENT_START + 1)
 
 // Visibility change
 NS_EVENT_MESSAGE(NS_VISIBILITY_START,     6300)
-NS_EVENT_MESSAGE(NS_VISIBILITY_CHANGE,    NS_VISIBILITY_START + 1)
+NS_EVENT_MESSAGE(eVisibilityChange,      NS_VISIBILITY_START + 1)
 
 // Details and Summary events.
 NS_EVENT_MESSAGE(NS_DETAILS_SUMMARY_EVENT_START,   6400)
diff --git a/widget/InputData.cpp b/widget/InputData.cpp
index 755e438ed9..6b7e6d3962 100644
--- a/widget/InputData.cpp
+++ b/widget/InputData.cpp
@@ -241,7 +241,7 @@ PanGestureInput::IsMomentum() const
 WidgetWheelEvent
 PanGestureInput::ToWidgetWheelEvent(nsIWidget* aWidget) const
 {
-  WidgetWheelEvent wheelEvent(true, NS_WHEEL_WHEEL, aWidget);
+  WidgetWheelEvent wheelEvent(true, eWheel, aWidget);
   wheelEvent.modifiers = this->modifiers;
   wheelEvent.time = mTime;
   wheelEvent.timeStamp = mTimeStamp;
@@ -313,7 +313,7 @@ DeltaModeForDeltaType(ScrollWheelInput::ScrollDeltaType aDeltaType)
 WidgetWheelEvent
 ScrollWheelInput::ToWidgetWheelEvent(nsIWidget* aWidget) const
 {
-  WidgetWheelEvent wheelEvent(true, NS_WHEEL_WHEEL, aWidget);
+  WidgetWheelEvent wheelEvent(true, eWheel, aWidget);
   wheelEvent.modifiers = this->modifiers;
   wheelEvent.time = mTime;
   wheelEvent.timeStamp = mTimeStamp;
diff --git a/widget/PuppetWidget.cpp b/widget/PuppetWidget.cpp
index 7ac0489ccc..06a35b8127 100644
--- a/widget/PuppetWidget.cpp
+++ b/widget/PuppetWidget.cpp
@@ -573,8 +573,7 @@ PuppetWidget::IMEEndComposition(bool aCancel)
 
   nsEventStatus status;
   bool noCompositionEvent = true;
-  WidgetCompositionEvent compositionCommitEvent(true, NS_COMPOSITION_COMMIT,
-                                                this);
+  WidgetCompositionEvent compositionCommitEvent(true, eCompositionCommit, this);
   InitEvent(compositionCommitEvent, nullptr);
   // SendEndIMEComposition is always called since ResetInputState
   // should always be called even if we aren't composing something.
diff --git a/widget/TextEventDispatcher.cpp b/widget/TextEventDispatcher.cpp
index 01e71daa24..adc450cfdd 100644
--- a/widget/TextEventDispatcher.cpp
+++ b/widget/TextEventDispatcher.cpp
@@ -191,7 +191,7 @@ TextEventDispatcher::StartComposition(nsEventStatus& aStatus)
   }
 
   mIsComposing = true;
-  WidgetCompositionEvent compositionStartEvent(true, NS_COMPOSITION_START,
+  WidgetCompositionEvent compositionStartEvent(true, eCompositionStart,
                                                mWidget);
   InitEvent(compositionStartEvent);
   rv = DispatchEvent(mWidget, compositionStartEvent, aStatus);
@@ -268,11 +268,11 @@ TextEventDispatcher::CommitComposition(nsEventStatus& aStatus,
   // End current composition and make this free for other IMEs.
   mIsComposing = false;
 
-  EventMessage message = aCommitString ? NS_COMPOSITION_COMMIT :
-                                         NS_COMPOSITION_COMMIT_AS_IS;
+  EventMessage message = aCommitString ? eCompositionCommit :
+                                         eCompositionCommitAsIs;
   WidgetCompositionEvent compositionCommitEvent(true, message, widget);
   InitEvent(compositionCommitEvent);
-  if (message == NS_COMPOSITION_COMMIT) {
+  if (message == eCompositionCommit) {
     compositionCommitEvent.mData = *aCommitString;
   }
   rv = DispatchEvent(widget, compositionCommitEvent, aStatus);
@@ -541,7 +541,7 @@ TextEventDispatcher::PendingComposition::Flush(TextEventDispatcher* aDispatcher,
 
   nsRefPtr<TextEventDispatcher> kungFuDeathGrip(aDispatcher);
   nsCOMPtr<nsIWidget> widget(aDispatcher->mWidget);
-  WidgetCompositionEvent compChangeEvent(true, NS_COMPOSITION_CHANGE, widget);
+  WidgetCompositionEvent compChangeEvent(true, eCompositionChange, widget);
   aDispatcher->InitEvent(compChangeEvent);
   compChangeEvent.mData = mString;
   if (mClauses) {
diff --git a/widget/TextEventDispatcher.h b/widget/TextEventDispatcher.h
index 0d64468a8b..08bf15bd14 100644
--- a/widget/TextEventDispatcher.h
+++ b/widget/TextEventDispatcher.h
@@ -112,7 +112,7 @@ public:
 
   /**
    * SetPendingCompositionString() sets new composition string which will be
-   * dispatched with NS_COMPOSITION_CHANGE event by calling Flush().
+   * dispatched with eCompositionChange event by calling Flush().
    *
    * @param aString         New composition string.
    */
@@ -255,7 +255,7 @@ private:
   nsWeakPtr mListener;
 
   // mPendingComposition stores new composition string temporarily.
-  // These values will be used for dispatching NS_COMPOSITION_CHANGE event
+  // These values will be used for dispatching eCompositionChange event
   // in Flush().  When Flush() is called, the members will be cleared
   // automatically.
   class PendingComposition
diff --git a/widget/TextEvents.h b/widget/TextEvents.h
index 2f251a0f84..41deadecaf 100644
--- a/widget/TextEvents.h
+++ b/widget/TextEvents.h
@@ -434,22 +434,22 @@ public:
 
   bool CausesDOMTextEvent() const
   {
-    return mMessage == NS_COMPOSITION_CHANGE ||
-           mMessage == NS_COMPOSITION_COMMIT ||
-           mMessage == NS_COMPOSITION_COMMIT_AS_IS;
+    return mMessage == eCompositionChange ||
+           mMessage == eCompositionCommit ||
+           mMessage == eCompositionCommitAsIs;
   }
 
   bool CausesDOMCompositionEndEvent() const
   {
-    return mMessage == NS_COMPOSITION_END ||
-           mMessage == NS_COMPOSITION_COMMIT ||
-           mMessage == NS_COMPOSITION_COMMIT_AS_IS;
+    return mMessage == eCompositionEnd ||
+           mMessage == eCompositionCommit ||
+           mMessage == eCompositionCommitAsIs;
   }
 
   bool IsFollowedByCompositionEnd() const
   {
-    return mOriginalMessage == NS_COMPOSITION_COMMIT ||
-           mOriginalMessage == NS_COMPOSITION_COMMIT_AS_IS;
+    return mOriginalMessage == eCompositionCommit ||
+           mOriginalMessage == eCompositionCommitAsIs;
   }
 };
 
@@ -514,7 +514,7 @@ public:
   void InitForQueryTextRect(uint32_t aOffset, uint32_t aLength,
                             bool aUseNativeLineBreak = true)
   {
-    NS_ASSERTION(mMessage == NS_QUERY_TEXT_RECT,
+    NS_ASSERTION(mMessage == eQueryTextRect,
                  "wrong initializer is called");
     mInput.mOffset = aOffset;
     mInput.mLength = aLength;
@@ -553,7 +553,7 @@ public:
   {
     NS_ASSERTION(mMessage == eQuerySelectedText ||
                  mMessage == eQueryCaretRect ||
-                 mMessage == NS_QUERY_TEXT_RECT,
+                 mMessage == eQueryTextRect,
                  "not querying selection or text rect");
     return mReply.mWritingMode;
   }
diff --git a/widget/WidgetEventImpl.cpp b/widget/WidgetEventImpl.cpp
index b309a86622..381982250f 100644
--- a/widget/WidgetEventImpl.cpp
+++ b/widget/WidgetEventImpl.cpp
@@ -136,12 +136,12 @@ bool
 WidgetEvent::HasIMEEventMessage() const
 {
   switch (mMessage) {
-    case NS_COMPOSITION_START:
-    case NS_COMPOSITION_END:
-    case NS_COMPOSITION_UPDATE:
-    case NS_COMPOSITION_CHANGE:
-    case NS_COMPOSITION_COMMIT_AS_IS:
-    case NS_COMPOSITION_COMMIT:
+    case eCompositionStart:
+    case eCompositionEnd:
+    case eCompositionUpdate:
+    case eCompositionChange:
+    case eCompositionCommitAsIs:
+    case eCompositionCommit:
       return true;
     default:
       return false;
diff --git a/widget/cocoa/TextInputHandler.mm b/widget/cocoa/TextInputHandler.mm
index cfa454109c..59603103e4 100644
--- a/widget/cocoa/TextInputHandler.mm
+++ b/widget/cocoa/TextInputHandler.mm
@@ -2714,7 +2714,7 @@ IMEInputHandler::DispatchCompositionChangeEvent(const nsString& aText,
 
   nsRefPtr<IMEInputHandler> kungFuDeathGrip(this);
 
-  WidgetCompositionEvent compositionChangeEvent(true, NS_COMPOSITION_CHANGE,
+  WidgetCompositionEvent compositionChangeEvent(true, eCompositionChange,
                                                 mWidget);
   compositionChangeEvent.time = PR_IntervalNow();
   compositionChangeEvent.mData = aText;
@@ -2740,7 +2740,7 @@ IMEInputHandler::DispatchCompositionCommitEvent(const nsAString* aCommitString)
   nsRefPtr<IMEInputHandler> kungFuDeathGrip(this);
 
   EventMessage message =
-    aCommitString ? NS_COMPOSITION_COMMIT : NS_COMPOSITION_COMMIT_AS_IS;
+    aCommitString ? eCompositionCommit : eCompositionCommitAsIs;
   WidgetCompositionEvent compositionCommitEvent(true, message, mWidget);
   compositionCommitEvent.time = PR_IntervalNow();
   if (aCommitString) {
@@ -2813,7 +2813,7 @@ IMEInputHandler::InsertTextAsCommittingComposition(
 
     // XXXmnakano Probably, we shouldn't emulate composition in this case.
     // I think that we should just fire DOM3 textInput event if we implement it.
-    WidgetCompositionEvent compStart(true, NS_COMPOSITION_START, mWidget);
+    WidgetCompositionEvent compStart(true, eCompositionStart, mWidget);
     InitCompositionEvent(compStart);
 
     DispatchEvent(compStart);
@@ -2903,7 +2903,7 @@ IMEInputHandler::SetMarkedText(NSAttributedString* aAttrString,
 
     mMarkedRange.location = SelectedRange().location;
 
-    WidgetCompositionEvent compStart(true, NS_COMPOSITION_START, mWidget);
+    WidgetCompositionEvent compStart(true, eCompositionStart, mWidget);
     InitCompositionEvent(compStart);
 
     DispatchEvent(compStart);
@@ -3186,7 +3186,7 @@ IMEInputHandler::FirstRectForCharacterRange(NSRange& aRange,
   LayoutDeviceIntRect r;
   bool useCaretRect = (aRange.length == 0);
   if (!useCaretRect) {
-    WidgetQueryContentEvent charRect(true, NS_QUERY_TEXT_RECT, mWidget);
+    WidgetQueryContentEvent charRect(true, eQueryTextRect, mWidget);
     charRect.InitForQueryTextRect(aRange.location, 1);
     DispatchEvent(charRect);
     if (charRect.mSucceeded) {
diff --git a/widget/cocoa/nsChildView.mm b/widget/cocoa/nsChildView.mm
index 490347bf99..b61fe9fd98 100644
--- a/widget/cocoa/nsChildView.mm
+++ b/widget/cocoa/nsChildView.mm
@@ -2764,7 +2764,7 @@ nsChildView::DispatchAPZWheelInputEvent(InputData& aEvent, bool aCanTriggerSwipe
     }
   }
 
-  WidgetWheelEvent event(true, NS_WHEEL_WHEEL, this);
+  WidgetWheelEvent event(true, eWheel, this);
 
   if (mAPZC) {
     uint64_t inputBlockId = 0;
@@ -2817,8 +2817,7 @@ nsChildView::DispatchAPZWheelInputEvent(InputData& aEvent, bool aCanTriggerSwipe
         MOZ_CRASH("unsupported event type");
         return;
     }
-    if (event.mMessage == NS_WHEEL_WHEEL &&
-        (event.deltaX != 0 || event.deltaY != 0)) {
+    if (event.mMessage == eWheel && (event.deltaX != 0 || event.deltaY != 0)) {
       ProcessUntransformedAPZEvent(&event, guid, inputBlockId, result);
     }
     return;
@@ -2862,8 +2861,7 @@ nsChildView::DispatchAPZWheelInputEvent(InputData& aEvent, bool aCanTriggerSwipe
       MOZ_CRASH("unexpected event type");
       return;
   }
-  if (event.mMessage == NS_WHEEL_WHEEL &&
-      (event.deltaX != 0 || event.deltaY != 0)) {
+  if (event.mMessage == eWheel && (event.deltaX != 0 || event.deltaY != 0)) {
     DispatchEvent(&event, status);
   }
 }
@@ -4819,7 +4817,7 @@ static int32_t RoundUp(double aDouble)
 {
   WidgetWheelEvent wheelEvent(true, msg, mGeckoChild);
   [self convertCocoaMouseWheelEvent:theEvent toGeckoEvent:&wheelEvent];
-  mExpectingWheelStop = (msg == NS_WHEEL_START);
+  mExpectingWheelStop = (msg == eWheelOperationStart);
   mGeckoChild->DispatchAPZAwareEvent(wheelEvent.AsInputEvent());
 }
 
@@ -4889,11 +4887,18 @@ PanGestureTypeForEvent(NSEvent* aEvent)
   }
 
   NSEventPhase phase = nsCocoaUtils::EventPhase(theEvent);
-  // Fire NS_WHEEL_START/STOP events when 2 fingers touch/release the touchpad.
+  // Fire eWheelOperationStart/End events when 2 fingers touch/release the
+  // touchpad.
   if (phase & NSEventPhaseMayBegin) {
-    [self sendWheelCondition:YES first:NS_WHEEL_STOP second:NS_WHEEL_START forEvent:theEvent];
+    [self sendWheelCondition:YES
+                       first:eWheelOperationEnd
+                      second:eWheelOperationStart
+                    forEvent:theEvent];
   } else if (phase & (NSEventPhaseEnded | NSEventPhaseCancelled)) {
-    [self sendWheelCondition:NO first:NS_WHEEL_START second:NS_WHEEL_STOP forEvent:theEvent];
+    [self sendWheelCondition:NO
+                       first:eWheelOperationStart
+                      second:eWheelOperationEnd
+                    forEvent:theEvent];
   }
 
   NSPoint locationInWindow = nsCocoaUtils::EventLocationForWindow(theEvent, [self window]);
diff --git a/widget/gtk/IMContextWrapper.cpp b/widget/gtk/IMContextWrapper.cpp
index 23f6606f0c..cf0d68b035 100644
--- a/widget/gtk/IMContextWrapper.cpp
+++ b/widget/gtk/IMContextWrapper.cpp
@@ -915,7 +915,7 @@ IMContextWrapper::OnSelectionChange(nsWindow* aCaller,
 
     // The focused editor might have placeholder text with normal text node.
     // In such case, the text node must be removed from a compositionstart
-    // event handler.  So, we're dispatching NS_COMPOSITION_START,
+    // event handler.  So, we're dispatching eCompositionStart,
     // we should ignore selection change notification.
     if (mCompositionState == eCompositionState_CompositionStartDispatched) {
         if (NS_WARN_IF(!mSelection.IsValid())) {
@@ -1303,7 +1303,7 @@ IMContextWrapper::DispatchCompositionStart(GtkIMContext* aContext)
         ("GTKIM: %p   DispatchCompositionStart(), FAILED, mCompositionStart=%u",
          this, mCompositionStart));
     mCompositionState = eCompositionState_CompositionStartDispatched;
-    WidgetCompositionEvent compEvent(true, NS_COMPOSITION_START,
+    WidgetCompositionEvent compEvent(true, eCompositionStart,
                                      mLastFocusedWindow);
     InitEvent(compEvent);
     nsCOMPtr<nsIWidget> kungFuDeathGrip = mLastFocusedWindow;
@@ -1364,7 +1364,7 @@ IMContextWrapper::DispatchCompositionChangeEvent(
         }
     }
 
-    WidgetCompositionEvent compositionChangeEvent(true, NS_COMPOSITION_CHANGE,
+    WidgetCompositionEvent compositionChangeEvent(true, eCompositionChange,
                                                   mLastFocusedWindow);
     InitEvent(compositionChangeEvent);
 
@@ -1439,8 +1439,8 @@ IMContextWrapper::DispatchCompositionCommitEvent(
 
     nsRefPtr<nsWindow> lastFocusedWindow(mLastFocusedWindow);
 
-    EventMessage message = aCommitString ? NS_COMPOSITION_COMMIT :
-                                           NS_COMPOSITION_COMMIT_AS_IS;
+    EventMessage message = aCommitString ? eCompositionCommit :
+                                           eCompositionCommitAsIs;
     mCompositionState = eCompositionState_NotComposing;
     mCompositionStart = UINT32_MAX;
     mCompositionTargetRange.Clear();
@@ -1449,7 +1449,7 @@ IMContextWrapper::DispatchCompositionCommitEvent(
     WidgetCompositionEvent compositionCommitEvent(true, message,
                                                   mLastFocusedWindow);
     InitEvent(compositionCommitEvent);
-    if (message == NS_COMPOSITION_COMMIT) {
+    if (message == eCompositionCommit) {
         compositionCommitEvent.mData = *aCommitString;
     }
 
@@ -1811,7 +1811,7 @@ IMContextWrapper::SetCursorPosition(GtkIMContext* aContext)
 
     WidgetQueryContentEvent charRect(true,
                                      useCaret ? eQueryCaretRect :
-                                                NS_QUERY_TEXT_RECT,
+                                                eQueryTextRect,
                                      mLastFocusedWindow);
     if (useCaret) {
         charRect.InitForQueryCaretRect(mSelection.mOffset);
@@ -1833,7 +1833,7 @@ IMContextWrapper::SetCursorPosition(GtkIMContext* aContext)
     if (!charRect.mSucceeded) {
         MOZ_LOG(gGtkIMLog, LogLevel::Error,
             ("GTKIM: %p   SetCursorPosition(), FAILED, %s was failed",
-             this, useCaret ? "eQueryCaretRect" : "NS_QUERY_TEXT_RECT"));
+             this, useCaret ? "eQueryCaretRect" : "eQueryTextRect"));
         return;
     }
 
diff --git a/widget/gtk/IMContextWrapper.h b/widget/gtk/IMContextWrapper.h
index f1933b39d8..aa3a745d2e 100644
--- a/widget/gtk/IMContextWrapper.h
+++ b/widget/gtk/IMContextWrapper.h
@@ -257,7 +257,7 @@ protected:
     // trying to delete the surrounding text.
     bool mIsDeletingSurrounding;
     // mLayoutChanged is true after OnLayoutChange() is called.  This is reset
-    // when NS_COMPOSITION_CHANGE is being dispatched.
+    // when eCompositionChange is being dispatched.
     bool mLayoutChanged;
     // mSetCursorPositionOnKeyEvent true when caret rect or position is updated
     // with no composition.  If true, we update candidate window position
diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
index f78cf83fac..9c4915eaf4 100644
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -2977,7 +2977,7 @@ nsWindow::OnKeyPressEvent(GdkEventKey *aEvent)
         }
         else {
             WidgetCompositionEvent compositionChangeEvent(
-                                     true, NS_COMPOSITION_CHANGE, this);
+                                     true, eCompositionChange, this);
             char16_t textString[3];
             textString[0] = H_SURROGATE(event.charCode);
             textString[1] = L_SURROGATE(event.charCode);
@@ -3031,7 +3031,7 @@ nsWindow::OnScrollEvent(GdkEventScroll *aEvent)
         mLastScrollEventTime == aEvent->time)
         return; 
 #endif
-    WidgetWheelEvent wheelEvent(true, NS_WHEEL_WHEEL, this);
+    WidgetWheelEvent wheelEvent(true, eWheel, this);
     wheelEvent.deltaMode = nsIDOMWheelEvent::DOM_DELTA_LINE;
     switch (aEvent->direction) {
 #if GTK_CHECK_VERSION(3,4,0)
diff --git a/widget/qt/nsWindow.cpp b/widget/qt/nsWindow.cpp
index 7a0aa32655..c01cf7eb14 100644
--- a/widget/qt/nsWindow.cpp
+++ b/widget/qt/nsWindow.cpp
@@ -1259,7 +1259,7 @@ nsEventStatus
 nsWindow::wheelEvent(QWheelEvent* aEvent)
 {
     // check to see if we should rollup
-    WidgetWheelEvent wheelEvent(true, NS_WHEEL_WHEEL, this);
+    WidgetWheelEvent wheelEvent(true, eWheel, this);
     wheelEvent.deltaMode = nsIDOMWheelEvent::DOM_DELTA_LINE;
 
     // negative values for aEvent->delta indicate downward scrolling;
diff --git a/widget/tests/TestWinTSF.cpp b/widget/tests/TestWinTSF.cpp
index 0bb71c55d9..70d44bb13e 100644
--- a/widget/tests/TestWinTSF.cpp
+++ b/widget/tests/TestWinTSF.cpp
@@ -1965,7 +1965,7 @@ TestApp::TestText(void)
    * Bug in eQueryTextContent handler
    * nsTextStore::SetText not calling SetSelection or InsertTextAtSelection
    * Bug in SetSelection or InsertTextAtSelection
-   *  eSetSelection bug or NS_COMPOSITION_* / NS_COMPOSITION_CHANGE bug
+   *  eSetSelection bug or eComposition* / eCompositionChange bug
    */
 
   if (!mMgr->GetFocusedStore()) {
diff --git a/widget/windows/IMMHandler.cpp b/widget/windows/IMMHandler.cpp
index b823e2c0ec..35ac6f7239 100644
--- a/widget/windows/IMMHandler.cpp
+++ b/widget/windows/IMMHandler.cpp
@@ -1250,7 +1250,7 @@ IMMHandler::HandleStartComposition(nsWindow* aWindow,
   mCompositionStart = selection.mOffset;
   mCursorPosition = NO_IME_CARET;
 
-  WidgetCompositionEvent event(true, NS_COMPOSITION_START, aWindow);
+  WidgetCompositionEvent event(true, eCompositionStart, aWindow);
   nsIntPoint point(0, 0);
   aWindow->InitEvent(event, &point);
   aWindow->DispatchWindowEvent(&event);
@@ -1525,7 +1525,7 @@ IMMHandler::HandleEndComposition(nsWindow* aWindow,
   }
 
   EventMessage message =
-    aCommitString ? NS_COMPOSITION_COMMIT : NS_COMPOSITION_COMMIT_AS_IS;
+    aCommitString ? eCompositionCommit : eCompositionCommitAsIs;
   WidgetCompositionEvent compositionCommitEvent(true, message, aWindow);
   nsIntPoint point(0, 0);
   aWindow->InitEvent(compositionCommitEvent, &point);
@@ -1897,7 +1897,7 @@ IMMHandler::DispatchCompositionChangeEvent(nsWindow* aWindow,
 
   nsIntPoint point(0, 0);
 
-  WidgetCompositionEvent event(true, NS_COMPOSITION_CHANGE, aWindow);
+  WidgetCompositionEvent event(true, eCompositionChange, aWindow);
 
   aWindow->InitEvent(event, &point);
 
@@ -2165,7 +2165,7 @@ IMMHandler::GetCharacterRectOfSelectedTextAt(nsWindow* aWindow,
   // If there is a caret and retrieving offset is same as the caret offset,
   // we should use the caret rect.
   if (offset != caretOffset) {
-    WidgetQueryContentEvent charRect(true, NS_QUERY_TEXT_RECT, aWindow);
+    WidgetQueryContentEvent charRect(true, eQueryTextRect, aWindow);
     charRect.InitForQueryTextRect(offset, 1);
     aWindow->InitEvent(charRect, &point);
     aWindow->DispatchWindowEvent(&charRect);
diff --git a/widget/windows/IMMHandler.h b/widget/windows/IMMHandler.h
index c01a8a441c..3514fb2da0 100644
--- a/widget/windows/IMMHandler.h
+++ b/widget/windows/IMMHandler.h
@@ -353,7 +353,7 @@ protected:
   bool GetTargetClauseRange(uint32_t *aOffset, uint32_t *aLength = nullptr);
 
   /**
-   * DispatchCompositionChangeEvent() dispatches NS_COMPOSITION_CHANGE event
+   * DispatchCompositionChangeEvent() dispatches eCompositionChange event
    * with clause information (it'll be retrieved by CreateTextRangeArray()).
    * I.e., this should be called only during composing.  If a composition is
    * being committed, only HandleCompositionEnd() should be called.
diff --git a/widget/windows/TSFTextStore.cpp b/widget/windows/TSFTextStore.cpp
index 0b6e0bd2c9..272b9d4ad5 100644
--- a/widget/windows/TSFTextStore.cpp
+++ b/widget/windows/TSFTextStore.cpp
@@ -1703,10 +1703,10 @@ TSFTextStore::FlushPendingActions()
         MOZ_LOG(sTextStoreLog, LogLevel::Debug,
                ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
                 "dispatching compositionstart event...", this));
-        WidgetCompositionEvent compositionStart(true, NS_COMPOSITION_START,
+        WidgetCompositionEvent compositionStart(true, eCompositionStart,
                                                 mWidget);
         mWidget->InitEvent(compositionStart);
-        // NS_COMPOSITION_START always causes NOTIFY_IME_OF_COMPOSITION_UPDATE.
+        // eCompositionStart always causes NOTIFY_IME_OF_COMPOSITION_UPDATE.
         // Therefore, we should wait to clear the locked content until it's
         // notified.
         mDeferClearingLockedContent = true;
@@ -1761,7 +1761,7 @@ TSFTextStore::FlushPendingActions()
         MOZ_LOG(sTextStoreLog, LogLevel::Debug,
                ("TSF: 0x%p   TSFTextStore::FlushPendingActions(), "
                 "dispatching compositionchange event...", this));
-        WidgetCompositionEvent compositionChange(true, NS_COMPOSITION_CHANGE,
+        WidgetCompositionEvent compositionChange(true, eCompositionChange,
                                                  mWidget);
         mWidget->InitEvent(compositionChange);
         compositionChange.mData = action.mData;
@@ -1773,7 +1773,7 @@ TSFTextStore::FlushPendingActions()
           action.mRanges->AppendElement(wholeRange);
         }
         compositionChange.mRanges = action.mRanges;
-        // When the NS_COMPOSITION_CHANGE causes a DOM text event,
+        // When the eCompositionChange causes a DOM text event,
         // the IME will be notified of NOTIFY_IME_OF_COMPOSITION_UPDATE.  In
         // such case, we should not clear the locked content until we notify
         // the IME of the composition update.
@@ -1796,11 +1796,11 @@ TSFTextStore::FlushPendingActions()
         MOZ_LOG(sTextStoreLog, LogLevel::Debug,
                ("TSF: 0x%p   TSFTextStore::FlushPendingActions(), "
                 "dispatching compositioncommit event...", this));
-        WidgetCompositionEvent compositionCommit(true, NS_COMPOSITION_COMMIT,
+        WidgetCompositionEvent compositionCommit(true, eCompositionCommit,
                                                  mWidget);
         mWidget->InitEvent(compositionCommit);
         compositionCommit.mData = action.mData;
-        // When the NS_COMPOSITION_COMMIT causes a DOM text event,
+        // When the eCompositionCommit causes a DOM text event,
         // the IME will be notified of NOTIFY_IME_OF_COMPOSITION_UPDATE.  In
         // such case, we should not clear the locked content until we notify
         // the IME of the composition update.
@@ -2459,7 +2459,7 @@ TSFTextStore::RecordCompositionUpdateAction()
   // the attribute, we have to find out all the ranges that have distinct
   // attribute values. Then we query for what the value represents through
   // the display attribute manager and translate that to TextRange to be
-  // sent in NS_COMPOSITION_CHANGE
+  // sent in eCompositionChange
 
   nsRefPtr<ITfProperty> attrPropetry;
   HRESULT hr = mContext->GetProperty(GUID_PROP_ATTRIBUTE,
@@ -2508,7 +2508,7 @@ TSFTextStore::RecordCompositionUpdateAction()
 
   TextRange newRange;
   // No matter if we have display attribute info or not,
-  // we always pass in at least one range to NS_COMPOSITION_CHANGE
+  // we always pass in at least one range to eCompositionChange
   newRange.mStartOffset = 0;
   newRange.mEndOffset = action->mData.Length();
   newRange.mRangeType = NS_TEXTRANGE_RAWINPUT;
@@ -3407,7 +3407,7 @@ TSFTextStore::GetACPFromPoint(TsViewCookie vcView,
     // offset since there is no inexpensive API to check it strictly.
     // XXX If we retrieve 2 bounding boxes, one is before the offset and
     //     the other is after the offset, we could resolve the offset.
-    //     However, dispatching 2 NS_QUERY_TEXT_RECT may be expensive.
+    //     However, dispatching 2 eQueryTextRect may be expensive.
 
     // So, use tentative offset for now.
     offset = charAtPt.mReply.mTentativeCaretOffset;
@@ -3566,15 +3566,15 @@ TSFTextStore::GetTextExt(TsViewCookie vcView,
     return TS_E_NOLAYOUT;
   }
 
-  // use NS_QUERY_TEXT_RECT to get rect in system, screen coordinates
-  WidgetQueryContentEvent event(true, NS_QUERY_TEXT_RECT, mWidget);
+  // use eQueryTextRect to get rect in system, screen coordinates
+  WidgetQueryContentEvent event(true, eQueryTextRect, mWidget);
   mWidget->InitEvent(event);
   event.InitForQueryTextRect(acpStart, acpEnd - acpStart);
   DispatchEvent(event);
   if (!event.mSucceeded) {
     MOZ_LOG(sTextStoreLog, LogLevel::Error,
            ("TSF: 0x%p   TSFTextStore::GetTextExt() FAILED due to "
-            "NS_QUERY_TEXT_RECT failure", this));
+            "eQueryTextRect failure", this));
     return TS_E_INVALIDPOS; // but unexpected failure, maybe.
   }
   // IMEs don't like empty rects, fix here
@@ -5412,8 +5412,8 @@ TSFTextStore::Content::ReplaceTextWith(LONG aStart,
     if (mComposition.IsComposing()) {
       // Emulate text insertion during compositions, because during a
       // composition, editor expects the whole composition string to
-      // be sent in NS_COMPOSITION_CHANGE, not just the inserted part.
-      // The actual NS_COMPOSITION_CHANGE will be sent in SetSelection
+      // be sent in eCompositionChange, not just the inserted part.
+      // The actual eCompositionChange will be sent in SetSelection
       // or OnUpdateComposition.
       MOZ_ASSERT(aStart >= mComposition.mStart);
       MOZ_ASSERT(aStart + aLength <= mComposition.EndOffset());
diff --git a/widget/windows/TSFTextStore.h b/widget/windows/TSFTextStore.h
index 7e3c680db0..0fa09b5fbe 100644
--- a/widget/windows/TSFTextStore.h
+++ b/widget/windows/TSFTextStore.h
@@ -335,7 +335,7 @@ protected:
     // Current copy of the active composition string. Only mString is
     // changed during a InsertTextAtSelection call if we have a composition.
     // mString acts as a buffer until OnUpdateComposition is called
-    // and mString is flushed to editor through NS_COMPOSITION_CHANGE.
+    // and mString is flushed to editor through eCompositionChange.
     // This way all changes are updated in batches to avoid
     // inconsistencies/artifacts.
     nsString mString;
diff --git a/widget/windows/WinMouseScrollHandler.cpp b/widget/windows/WinMouseScrollHandler.cpp
index 070920db1a..0d6a9e983d 100644
--- a/widget/windows/WinMouseScrollHandler.cpp
+++ b/widget/windows/WinMouseScrollHandler.cpp
@@ -626,23 +626,23 @@ MouseScrollHandler::HandleMouseWheelMessage(nsWindowBase* aWidget,
   // Grab the widget, it might be destroyed by a DOM event handler.
   nsRefPtr<nsWindowBase> kungFuDethGrip(aWidget);
 
-  WidgetWheelEvent wheelEvent(true, NS_WHEEL_WHEEL, aWidget);
+  WidgetWheelEvent wheelEvent(true, eWheel, aWidget);
   if (mLastEventInfo.InitWheelEvent(aWidget, wheelEvent, modKeyState)) {
     MOZ_LOG(gMouseScrollLog, LogLevel::Info,
       ("MouseScroll::HandleMouseWheelMessage: dispatching "
-       "NS_WHEEL_WHEEL event"));
+       "eWheel event"));
     aWidget->DispatchWheelEvent(&wheelEvent);
     if (aWidget->Destroyed()) {
       MOZ_LOG(gMouseScrollLog, LogLevel::Info,
         ("MouseScroll::HandleMouseWheelMessage: The window was destroyed "
-         "by NS_WHEEL_WHEEL event"));
+         "by eWheel event"));
       mLastEventInfo.ResetTransaction();
       return;
     }
   }
   else {
     MOZ_LOG(gMouseScrollLog, LogLevel::Info,
-      ("MouseScroll::HandleMouseWheelMessage: NS_WHEEL_WHEEL event is not "
+      ("MouseScroll::HandleMouseWheelMessage: eWheel event is not "
        "dispatched"));
   }
 }
@@ -662,7 +662,7 @@ MouseScrollHandler::HandleScrollMessageAsMouseWheelMessage(nsWindowBase* aWidget
 
   ModifierKeyState modKeyState = GetModifierKeyState(aMessage);
 
-  WidgetWheelEvent wheelEvent(true, NS_WHEEL_WHEEL, aWidget);
+  WidgetWheelEvent wheelEvent(true, eWheel, aWidget);
   double& delta =
    (aMessage == MOZ_WM_VSCROLL) ? wheelEvent.deltaY : wheelEvent.deltaX;
   int32_t& lineOrPageDelta =
@@ -819,7 +819,7 @@ MouseScrollHandler::LastEventInfo::InitWheelEvent(
                                      WidgetWheelEvent& aWheelEvent,
                                      const ModifierKeyState& aModKeyState)
 {
-  MOZ_ASSERT(aWheelEvent.mMessage == NS_WHEEL_WHEEL);
+  MOZ_ASSERT(aWheelEvent.mMessage == eWheel);
 
   // XXX Why don't we use lParam value? We should use lParam value because
   //     our internal message is always posted by original message handler.
diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index 44584849db..07e422d5cb 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -5399,8 +5399,7 @@ nsWindow::ProcessMessage(UINT msg, WPARAM& wParam, LPARAM& lParam,
         nsPointWin touchPoint;
         touchPoint = gestureinfo->ptsLocation;
         touchPoint.ScreenToClient(mWnd);
-        WidgetGestureNotifyEvent gestureNotifyEvent(true,
-                                   NS_GESTURENOTIFY_EVENT_START, this);
+        WidgetGestureNotifyEvent gestureNotifyEvent(true, eGestureNotify, this);
         gestureNotifyEvent.refPoint = LayoutDeviceIntPoint::FromUntyped(touchPoint);
         nsEventStatus status;
         DispatchEvent(&gestureNotifyEvent, status);
@@ -6343,7 +6342,7 @@ bool nsWindow::OnGesture(WPARAM wParam, LPARAM lParam)
 
     nsEventStatus status;
 
-    WidgetWheelEvent wheelEvent(true, NS_WHEEL_WHEEL, this);
+    WidgetWheelEvent wheelEvent(true, eWheel, this);
 
     ModifierKeyState modifierKeyState;
     modifierKeyState.InitInputEvent(wheelEvent);