Merge branch 't/13143'

Author: oleq

CHANGES.md

@@ -19,6 +19,7 @@ Fixed Issues:
 * [#13420](http://dev.ckeditor.com/ticket/13420): Fixed: The [Auto Embed](http://ckeditor.com/addon/autoembed) plugin ignores encoded characters in URL parameters.
 * [#13184](http://dev.ckeditor.com/ticket/13184): Fixed: Web page reloaded after drop on editor UI.
 * [#13410](http://dev.ckeditor.com/ticket/13410): Fixed: Error thrown in the [Auto Embed](http://ckeditor.com/addon/autoembed) plugin when undoing right after pasting a link.
+* [#13143](http://dev.ckeditor.com/ticket/13143): [Edge] Fixed: Focus lost while opening the panel.
 
 ## CKEditor 4.5.1
 

plugins/floatpanel/plugin.js

@@ -1,4 +1,4 @@
-/**
+/**
  * @license Copyright (c) 2003-2015, CKSource - Frederico Knabben. All rights reserved.
  * For licensing, see LICENSE.md or http://ckeditor.com/license
  */
@@ -153,8 +153,8 @@ CKEDITOR.plugins.add( 'floatpanel', {
 
 				var element = this.element,
 					iframe = this._.iframe,
-					// Non IE prefer the event into a window object.
-					focused = CKEDITOR.env.ie ? iframe : new CKEDITOR.dom.window( iframe.$.contentWindow ),
+					// Edge prefers iframe's window to the iframe, just like the rest of the browsers (#13143).
+					focused = CKEDITOR.env.ie && !CKEDITOR.env.edge ? iframe : new CKEDITOR.dom.window( iframe.$.contentWindow ),
 					doc = element.getDocument(),
 					positionedAncestor = this._.parentElement.getPositionedAncestor(),
 					position = offsetParent.getDocumentPosition( doc ),