I have a window with some buttons at the top (in a horiz Box), a label at the bottom, and a DrawingArea in the middle, all in a vert Box.

I want the DrawingArea to occupy all the available space in the middle.

After showAll() I call getSize() to retrieve the actual window size.

But how can I find out how much space is available in the middle so that I can call DrawingArea.setSizeRequest() to occupy all the available space?