The new menu is much more efficient for the user:
* Less tall items makes it much easier to select among many completions.
* Exactly wide enough for widest item.
* Tall enough to show all items (instead of just 3 as before).
* Uses a maximum width and height defined by the screen edges and some Cocoa-like constants.
The menu should appear above other normal windows and controls like a regular CPMenu. To do this, put the pop up in its own window with the `CPPopUpMenuWindowLevel` window level.
Alexander Ljungberg