optgroup issues

[elavelle]

1 - If the selected window is sortable, then only the entire optgroup sorts. There's no way to sort individual list items

2 - If the last item in a group is removed from the selected window with '-', then the group label remains in the selected window, even though there are no items in the group

3 - If the selected window is sortable, then the styling is wrong: the sort arrows on the selected item overlap with the first letter of the selected item text

The simplest fix for (1) and (2) might be to remove optgroups in the selected list, and leave them in the available list. It doesn't seem to me to be important to have groups in the selected list. I can't immediately see how to do this, though.