UIButton and image transparency

Well, the best advice I can give you is don't use com.jmex.ui.*. We are removing it because the main developer has moved on from it and it's fallen in disrepair. There are two other efforts that I would focus on (BUI and NUI). BUI is actively developed by Three Rings and might be the better bet.

http://www.jmonkeyengine.com/jmeforum/index.php?topic=1648.0 is the thread regarding BUI.

Sorry, for any confusion with all the UI/widget choices.