wxPython && wxGlade

[Simon Dahlbacka]

basically, you can just stack an outer vertical box sizer with two
items and in the upper "slot" you put a horizontal box sizer with your
two buttons and in the bottom slot you put the big button

hope this helps

/Simon

ps. as this is a wxpython related question, you might get better
answers on the wxpython mailinglist (but afaik, this is the way this
particular thing is done).