If I have a ListBox that already has some items selected (i.e. a user has selected items, and then moved on to another box that causes a postback, so the listbox is redrawn), how do I cause the box to ...

I've got a listbox that holds a list of groups. Users can select a group, hit the remove button and the group should be removed from the listbox. The only problem is that no matter which group you ...