You can look at the difference between GetSize() and GetClientSize() to
get a good estimate of the size of the frame decorations plus any "bars"
in the frame.
I think there was an issue related to this on wxGTK up to 2.8, because
getting the actual size of the caption bar and such was done in an
unreliable way, but that is supposed to have been fixed in 2.9. The
other platforms should give you accurate sizes.
--
Robin Dunn
Software Craftsman
http://wxPython.org