How to get the width and height of the drawable area of a window in pixels?

I can get the figure size in pixels like this:

 set(gcf,'units','normalized','position',[0 0 1 1])
 set(gcf,'units','pixels')
 gcf_position = get(gcf,'position');
 figure_width = gcf_position(3);
 figure_height = gcf_position(4);

But there is a title bar and buttons area at the top of the window, and I want to get its heigh to get the usable maximal axis height. How to do this?