I'm starting a new project using the Matisse tools -- nice job, BTW -- and a simple set of Radio buttons doesn't deselect/select the way radio buttons should. I did assign them to a button group, but when I go to design preview, they still act like checkboxes.

I'm sure I'm missing something simple here...

I don't think preview mode actually 'runs' the code and there for honors the buttongroup requirement, try running your class, it should work.