Colorbox Integration

I tried the same code as
http://drupal.org/node/1691886#comment-6289220 but it didnot worked

For colorbox though, css should be assigned in Link-advance tab and not Image-advanced tab.

I also tried

CKEDITOR.on( 'dialogDefinition', function( ev )
	{
		// Take the dialog name and its definition from the event data.
		var dialogName = ev.data.name;
		var dialogDefinition = ev.data.definition;
 
		// Check if the definition is from the dialog window you are interested in (the "Link" dialog window).
		if ( dialogName == 'link' )
		{
			// Get a reference to the "Link Info" tab.
			var infoTab = dialogDefinition.getContents( 'advanced' );
 
			// Set the default value for the URL field.
			var cssField = infoTab.get( 'advCSSClasses' );
			cssField['default'] = 'colorbox-load';
		}
	});

default's to colorbox-load, but when image is inserted using image icon, default colorbox-load just vanishes from Link-advance tab.

What I a doing wrong

Thanks