Ticket #4522: 4522_3.patch

_source/plugins/undo/plugin.js

@@ -130 +130 @@
                         this.contents = this.contents.replace( /\s+_cke_expando=".*?"/g, '' );
         }
 
+        // Attributes that browser may changing them when setting via innerHTML. 
+        var protectedAttrs = /\b(?:href|src|name)="[^"]*?"/gi;
+
         Image.prototype =
         {
                 equals : function( otherImage, contentOnly )
                 {
-                        if ( this.contents != otherImage.contents )
+                        var thisContents = this.contents,
+                                otherContents = otherImage.contents;
+
+                        // For IE6/7 : Comparing only the protected attribute values but not the original ones.(#4522)
+                        if( CKEDITOR.env.ie && ( CKEDITOR.env.ie7Compat || CKEDITOR.env.ie6Compat ) )
+                        {
+                                thisContents = thisContents.replace( protectedAttrs, '' );
+                                otherContents = otherContents.replace( protectedAttrs, '' );
+                        }
+
+                        if( thisContents != otherContents )
                                 return false;
 
                         if ( contentOnly )