Also, in general don't expect minsize to work as expected with Tk. :) In practice it tends to be platform specific and buggy.
Also, take a look at your expand and fill settings for everything when things aren't sizing the way you expect. Often by setting the right things to expand (and the right things not to), you can get the right sizes without creating brittle code that thinks it knows how many pixels a buttom is supposed to be. (your user might be using a font 10x larger than you thought was probable, or other weird things)
