is there Any Dropdown <select> contains checkboxes?

I need a dropdown menu <select> which contains multiple checkboxes. so people can drop down and select many options (all the checkboxes should be inside the dropdown)

Sometimes this is called开发者_JS百科 a combobox (just to make everyone understands what I'm looking for)

I want this with javascript/css & not java applet or flash.

I think this is the thing you're describing - http://code.google.com/p/dropdown-check-list/