in reply to Stretchy grids in Tk
I don't have Tk on this machine to test this with, but you may want to try creating your widgets with -expand => 1 to expand the allocation rectangle to fill all the unfilled space, and -fill => 'both' to make the widget take up the full space of the allocation rectangle.
Let me know if there's any problems with this as I'll have my normal Tk-equipped machine again soon so could Play.
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