Hi Kevin,
it's been a while since I played with the multi-select (which is only mildly useful it must be said, as it has some rather sever limitations - like only 1 column, no sorting etc) - but as I recall it's a "drop list" control, with multi-select set on.
It becomes not a drop list, but a normal browse list, so the multi-selected items are visible.
It does support the shift-clcik, ctrl-click behaviour though.
cheers
Bruce