GUI features - Transparency and masks?

I am looking to build a GUI for my little demo game that has custom skins. Having looked at the GUI systems listed here in the blitz site and forums, I cannot tell if any support, or don't support, the 2 following features:

1. Buttons/windows with alpha transparency masks? Example: A window with a background that fades from Opaque to Transparent.

2. Along the same lines...Buttons and windows with arbitrary shapes defined by an image/mask. Example: A window shaped like a face.

Any info would be appreciated.
Thanks,

1) FUI (I use it, and it does), NGUI, and Swift's GUI do it I know, I'm not sure about the others.

2) Not quite sure. I know FUI has 'skins' but that might just be color scheme changes. I think Sswift's GUI could do it, but it doesn't have windows style gadget as it is more designed for games.