From 19bc82d7525a23eb8f9cffded03461e69f71a110 Mon Sep 17 00:00:00 2001
From: janekptacijarabaci <janekptacijarabaci@seznam.cz>
Date: Sat, 22 Apr 2017 13:53:42 +0200
Subject: [PATCH] [minor fix] If the master password is set, sometimes throws
 an error

---
 toolkit/content/widgets/popup.xml | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/toolkit/content/widgets/popup.xml b/toolkit/content/widgets/popup.xml
index 2e75950373..26fce8a104 100644
--- a/toolkit/content/widgets/popup.xml
+++ b/toolkit/content/widgets/popup.xml
@@ -262,12 +262,13 @@
       <handler event="popupshowing"><![CDATA[
         // Capture the previous focus before has a chance to get set inside the panel
         try {
-          this._prevFocus = document.commandDispatcher.focusedElement;
-          if (this._prevFocus)
+          this._prevFocus = Components.utils
+                            .getWeakReference(document.commandDispatcher.focusedElement);
+          if (this._prevFocus.get())
             return;
         } catch (ex) { }
 
-        this._prevFocus = document.activeElement;
+        this._prevFocus = Components.utils.getWeakReference(document.activeElement);
       ]]></handler>
       <handler event="popupshown"><![CDATA[
         // Fire event for accessibility APIs
@@ -284,7 +285,7 @@
       ]]></handler>
       <handler event="popuphidden"><![CDATA[
         var currentFocus = this._currentFocus;
-        var prevFocus = this._prevFocus;
+        var prevFocus = this._prevFocus ? this._prevFocus.get() : null;
         this._currentFocus = null;
         this._prevFocus = null;
         if (prevFocus && currentFocus && this.getAttribute("norestorefocus") != "true") {