Tricky resizing problem

[Matt Carlson <mindbender lokigames com>]

I've been stewing over this for a bit and can't seem to come up with a
reasonable answer.

I am working on a program that has a menubar and a drawing area in the
main window.  When the user attempts to resize the window, the program
obtains the new dimensions, calculates the closest size among several
predetermined sizes, and resizes the window to the result of the
analysis.  My problem is that the newly calculated size is intended for
the drawing area and not the window.  Is there a way to resize a window
around the new size of the widgets it contains?  If not, how can I
obtain the information to determine this "manually"?