Combobox with fixed length

Is there anyway to limit the length of the combobox. I mean, if I have 60 elements in my combobox, I only want the first 10 to appear. The other 50 have to become visible through a scrollbar. Like a real <select> behaviour.

The combo's popup contains an AW list. Look at -

http://www.activewidgets.com/aw.ui.list/

and especially the view model.