I love the umenu and autopopulate, it's fantastic. Plus I like that you can move around with the up/down arrows, or without dragging, if you click and release on the actual menu without selecting right away. So while you're using the arrows/mouse to move through the items, you can hit Enter to select one and close the menu, or hit Tab to close without selecting. Is there a way to select without closing the list?
Depending on whether it's a real pain to add, I'd love to see:
Enter -- selects and closes
Tab -- selects without closing
Backspace -- closes, no selection
Mouse click -- selects and closes
Shift-click -- selects without closing (maybe)
The combination of arrow keys/mouse and Tab in this design would make file browsing even better with the umenu.
If I'm missing something that's already there, do tell...