You can extend over window bounds, what I meant is the dropdown should open up or give you a property to allow you this option, also Flex dropdowns had the property you can set how many items are visible at a time. I learned Adobe AIR because my employer liked it better then Qt at that time and he also trusted Adobe products, moving from c++/Qt (and previous C# Winforms and WPF) to AIR was a downgrade in some aspects but after you learn it you can do your job and implement most of the things fast. What do you use for creating native apps for Windows, I do not know what is the prefered thing this days?