Issue #2019 - Do not dispatch keypress event for non-printable keys.

This will prevent the keypress DOM event from firing on keypresses
that do not produce printable keys (e.g. editing nav keys) in content.
This should not affect any chrome events that are in use.
Event dispatch can be re-enabled if necessary with the added pref.

editor/libeditor/HTMLEditor.cpp

@@ -664,8 +664,7 @@ HTMLEditor::HandleKeyPressEvent(nsIDOMKeyEvent* aKeyEvent)
       return TypedText(NS_LITERAL_STRING("\t"), eTypedText);
     }
     case NS_VK_RETURN:
-      if (nativeKeyEvent->IsControl() || nativeKeyEvent->IsAlt() ||
-          nativeKeyEvent->IsMeta() || nativeKeyEvent->IsOS()) {
+      if (!nativeKeyEvent->IsInputtingLineBreak()) {
         return NS_OK;
       }
       aKeyEvent->AsEvent()->PreventDefault(); // consumed
@@ -677,11 +676,7 @@ HTMLEditor::HandleKeyPressEvent(nsIDOMKeyEvent* aKeyEvent)
       return TypedText(EmptyString(), eTypedBreak);
   }
 
-  // NOTE: On some keyboard layout, some characters are inputted with Control
-  // key or Alt key, but at that time, widget sets FALSE to these keys.
-  if (!nativeKeyEvent->mCharCode || nativeKeyEvent->IsControl() ||
-      nativeKeyEvent->IsAlt() || nativeKeyEvent->IsMeta() ||
-      nativeKeyEvent->IsOS()) {
+  if (!nativeKeyEvent->IsInputtingText()) {
     // we don't PreventDefault() here or keybindings like control-x won't work
     return NS_OK;
   }

editor/libeditor/TextEditor.cpp

@@ -397,20 +397,14 @@ TextEditor::HandleKeyPressEvent(nsIDOMKeyEvent* aKeyEvent)
       return TypedText(NS_LITERAL_STRING("\t"), eTypedText);
     }
     case NS_VK_RETURN:
-      if (IsSingleLineEditor() || nativeKeyEvent->IsControl() ||
-          nativeKeyEvent->IsAlt() || nativeKeyEvent->IsMeta() ||
-          nativeKeyEvent->IsOS()) {
+      if (IsSingleLineEditor() || !nativeKeyEvent->IsInputtingLineBreak()) {
         return NS_OK;
       }
       aKeyEvent->AsEvent()->PreventDefault();
       return TypedText(EmptyString(), eTypedBreak);
   }
 
-  // NOTE: On some keyboard layout, some characters are inputted with Control
-  // key or Alt key, but at that time, widget sets FALSE to these keys.
-  if (!nativeKeyEvent->mCharCode || nativeKeyEvent->IsControl() ||
-      nativeKeyEvent->IsAlt() || nativeKeyEvent->IsMeta() ||
-      nativeKeyEvent->IsOS()) {
+  if (!nativeKeyEvent->IsInputtingText()) {
     // we don't PreventDefault() here or keybindings like control-x won't work
     return NS_OK;
   }

modules/libpref/init/all.js

@@ -231,6 +231,10 @@ pref("dom.keyboardevent.code.enabled", true);
 // even if this is true).
 pref("dom.keyboardevent.dispatch_during_composition", false);
 
+// If this is true, TextEventDispatcher dispatches keypress events
+// for the input of non-printable characters (content only).
+pref("dom.keyboardevent.keypress.dispatch_non_printable_in_content", false);
+
 // Whether URL,Location,Link::GetHash should be percent encoded
 // in setter and percent decoded in getter (old behaviour = true)
 pref("dom.url.encode_decode_hash", true);

widget/TextEventDispatcher.cpp

@@ -21,6 +21,7 @@ namespace widget {
  *****************************************************************************/
 
 bool TextEventDispatcher::sDispatchKeyEventsDuringComposition = false;
+bool TextEventDispatcher::sDispatchKeyPressEventNonPrintableInContent = false;
 
 TextEventDispatcher::TextEventDispatcher(nsIWidget* aWidget)
   : mWidget(aWidget)
@@ -36,6 +37,10 @@ TextEventDispatcher::TextEventDispatcher(nsIWidget* aWidget)
       &sDispatchKeyEventsDuringComposition,
       "dom.keyboardevent.dispatch_during_composition",
       false);
+    Preferences::AddBoolVarCache(
+      &sDispatchKeyPressEventNonPrintableInContent,
+      "dom.keyboardevent.keypress.dispatch_non_printable_in_content",
+      false);
     sInitialized = true;
   }
 }
@@ -531,6 +536,13 @@ TextEventDispatcher::DispatchKeyboardEventInternal(
     }
   }
 
+  if (!sDispatchKeyPressEventNonPrintableInContent &&
+      keyEvent.mMessage == eKeyPress &&
+      !keyEvent.IsInputtingText() &&
+      !keyEvent.IsInputtingLineBreak()) {
+    keyEvent.mFlags.mOnlySystemGroupDispatchInContent = true;
+  }
+
   DispatchInputEvent(mWidget, keyEvent, aStatus);
   return true;
 }

widget/TextEventDispatcher.h

@@ -399,6 +399,10 @@ private:
   // is a composition.
   static bool sDispatchKeyEventsDuringComposition;
 
+  // If this is true, keypress events for non-printable keys are dispatched to
+  // event listeners of the system event group in web content.
+  static bool sDispatchKeyPressEventNonPrintableInContent;
+
   nsresult BeginInputTransactionInternal(
              TextEventDispatcherListener* aListener,
              InputTransactionType aType);

widget/TextEvents.h

@@ -183,6 +183,30 @@ public:
     return IsKeyEventOnPlugin(mMessage);
   }
 
+  bool IsInputtingText() const
+  {
+    // NOTE: On some keyboard layouts, some characters are put in with Control
+    //       or Alt keys, but at that time, widget unsets the modifier flag
+    //       from the eKeyPress event, so it does not count as a modifier in
+    //       this check.
+    return mMessage == eKeyPress &&
+           mCharCode &&
+           !(mModifiers & (MODIFIER_ALT |
+                           MODIFIER_CONTROL |
+                           MODIFIER_META |
+                           MODIFIER_OS));
+  }
+
+  bool IsInputtingLineBreak() const
+  {
+    return mMessage == eKeyPress &&
+           mKeyNameIndex == KEY_NAME_INDEX_Enter &&
+           !(mModifiers & (MODIFIER_ALT |
+                           MODIFIER_CONTROL |
+                           MODIFIER_META |
+                           MODIFIER_OS));
+  }
+
   virtual WidgetEvent* Duplicate() const override
   {
     MOZ_ASSERT(mClass == eKeyboardEventClass,