1. Click on puzzle icon to "Add gadget by URL."
2. Enter http://blah.appspot.com/wave/sudoku/sudoku.xml
3. Click the Add button.

You should see a sudoku grid but you only see an empty box 20 px high.

Work around for new gadgets: Add a call to gadgets.window.adjustHeight()in the gadget initialize function and anytime you change the viewport sizing (see Paul Lindner's comment in wave-dev "Gadget Hieght" chain).

For existing gadgets: a code change is needed to resize the gadget window.