Index: /CKEditor/trunk/_source/core/tools.js
===================================================================
--- /CKEditor/trunk/_source/core/tools.js	(revision 3374)
+++ /CKEditor/trunk/_source/core/tools.js	(revision 3375)
@@ -63,14 +63,13 @@
 		clone : function( object )
 		{
-			var clone = {};
+			if( object === null || typeof( object ) != 'object') 
+				return object;
+				
+			var clone = new object.constructor();
 
 			for ( var propertyName in object )
 			{
 				var property = object[ propertyName ];
-
-				if ( typeof property == 'object' )
-					property = this.clone( property );
-
-				clone[ propertyName ] = property;
+				clone[ propertyName ] = this.clone( property );
 			}