The code

$.extend( $.ui, {

$.ui.plugin is deprecated. Use the proxy pattern instead. plugin: {

add: function( module, option, set ) {

var proto = $.ui[ module ].prototype; for ( var i in set ) {

Is using the for...in syntax. If the prototype of the Javascript object has been extended this breaks. Instead it should probably use for ( var j = 0; j < set.length; ++j )

Sorry I am not very familiar with Javascript or jQuery so it would be a lot of effort to make a test case. I'm seeing the problem on a private site.

Minimal test case:

$('<select><option>Option</option></select>')
    .appendTo('body')
    .bind('remove', function() {
        alert('This dialog should show...');
    })
    .remove();

This code used to work with jQuery 1.3 but no longer works with 1.4, breaking certain widgets that are meant to be attached to <select> elements (in my case, jquery-dropdownchecklist).

The bug is caused by behaviour changed in jQuery 1.4: $.makeArray (called by $.fn.add) now checks for a length property, which a <select> DOM element will have.

ui.dialog.js line 579

this.instances.splice($.inArray(this.instances, $el), 1);

I think it should be $.inArray($el, this.instances). Did i misunderstand it?