Selected items in the listbox will show up in the UL below. Click on an item in the UL and it will remove it from the listbox and remove itself from the UL.
Reproduce Bug: http://jsfiddle.net/rkw79/mmBKf/2/
- Select an item in the listbox
- Click on that item in the UL, it will disappear and the listbox will show it as unselected
- Click on that same item in the listbox
Notice that the event is fired, but the item is not added
Now do the same steps, except use .prop('selected','') instead of .removeProp('selected'): http://jsfiddle.net/rkw79/mmBKf/3/