PopupMenu control?

I want a simple PopupMenu control. I’m using the ComboBox since it approximates the desired behavior, but I don’t like how the menu appears below the combo box. What I want is for the menu to pop in such a way that the currently selected item in the menu appears under the mouse, and perfectly lined up with the text in the control. I’m talking about how they behave on the Macintosh (I think).

Here’s an example. In this image you can see that the menu popped with the 4th item from the top under the mouse, since that was the current item before the pop:

Combo boxes do work like that if they have a lot of items - try the one on the ‘misc widgets’ demo page. The logic it uses is that if there’s space to show the whole menu without covering the combo box, then it does so, but if it needs to overlap the box, then it makes sure the right item is positioned above it. Not really sure if that’s good or bad, TBH.