Effective size of drawing area

[Krzysztof <kj limes com pl>]

Assume that:

window default size is 300x300

window has box with menu bar and drawing area:

box = new Gtk::Box(Gtk::ORIENTATION_VERTICAL);
box->pack_start(menuBar, Gtk::PACK_SHRINK);
box->pack_start(*darea, Gtk::PACK_EXPAND_WIDGET);

What is and how to determine the size of area where I can actually do 
all drawing?


--
Regards
Krzysztof J.