how to create "client area" widget?

[Ivan Popivanov <popivan gmx net>]

I guess this question has been asked many times here:-), but I was 
unable to find anything in the archives. So, what's the way to create 
say a DrawingArea widget that covers the client area of the main window, 
and have the DrawingArea resize automatically?

What will happen if there are toolbars, menus etc? Does GTK 
automatically adjust the size and the position of the client area 
window, or the application has to take care for that?

TIA,
Ivan