Index: /CKEditor/trunk/_source/plugins/dialog/plugin.js
===================================================================
--- /CKEditor/trunk/_source/plugins/dialog/plugin.js	(revision 5447)
+++ /CKEditor/trunk/_source/plugins/dialog/plugin.js	(revision 5448)
@@ -2787,5 +2787,5 @@
 
 		// Remove dialog cover on last instance destroy.
-		if ( CKEDITOR.tools.isEmpty( CKEDITOR.instances ) );
+		if ( CKEDITOR.tools.isEmpty( CKEDITOR.instances ) && coverElement )
 			coverElement.remove();
 	});