Index: /CKEditor/trunk/CHANGES.html
===================================================================
--- /CKEditor/trunk/CHANGES.html	(revision 5703)
+++ /CKEditor/trunk/CHANGES.html	(revision 5704)
@@ -51,5 +51,6 @@
 		<li><a href="http://dev.fckeditor.net/ticket/5079">#5079</a> : Page break in lists move to above the list when you switch from WYSIWYG to HTML mode and back.</li>
 		<li><a href="http://dev.fckeditor.net/ticket/5436">#5436</a> : IE: Cursor goes to next Table Cell after we insert a Smiley in the Table Cell.</li>
-		<li><a href="http://dev.fckeditor.net/ticket/5580">#5580</a> : Maximize does not work properly in the Office 2003 and V2 skins.</li>  
+		<li><a href="http://dev.fckeditor.net/ticket/5580">#5580</a> : Maximize does not work properly in the Office 2003 and V2 skins.</li>  ble Cell.</li>
+		<li><a href="http://dev.fckeditor.net/ticket/5843">#5843</a> : In CKEditor 3.3: When we set the focus in the 'instanceReady' event, FF3.6 is giving js error.</li>
 	</ul>
 	<h3>
Index: /CKEditor/trunk/_source/plugins/selection/plugin.js
===================================================================
--- /CKEditor/trunk/_source/plugins/selection/plugin.js	(revision 5703)
+++ /CKEditor/trunk/_source/plugins/selection/plugin.js	(revision 5704)
@@ -18,5 +18,5 @@
 			// releasing the WYSIWYG mode, so we need to check it first.
 			var sel = this.getSelection();
-			if ( !sel )
+			if ( !sel || !sel.document.getWindow().$ )
 				return;