[gtkmm] ScrolledWindow containing a DrawingArea, does not "respond"

[Giannis Georgalis <jgeorgal uoc gr>]

Hello,

I'm trying to insert a DrawingArea in a ScrolledWindow, so if the
top-level window is smaller than the size of the image (that I draw in
the DrawingArea), the user will be able to see the whole picture by
scrolling.

I've read a lot of gtk+2.0 "sample" code, which suggested that You just
add the DrawingArea inside the ScrolledWindow (with a viewport - which
is done automatically in gtkmm) and everything should work...

Thus,

	scrolledWindow.set_policy(Gtk::POLICY_ALWAYS, Gtk::POLICY_ALWAYS);
	scrolledWindow.add(*this);   // I'm inside a DrawingArea.
	topLevelWindow.add(scrolledWindow);

However, the scroll-bars remain inactive. That is, they cannot be
used to navigate through the image no matter how small I make a
window.

I suspected that this problem might have been because the
scrolledWindow couldn't get the top-level window size, so I did this:

	int window_width = 0, window_height = 0;
	topLevelWindow.get_size(window_width, window_height);
	scrolledWindow.set_size_request(window_width, window_height);

with no effect at all, however :-(

Any hint is highly appreciated.

Thank you,
Giannis

-- 
question = ( to ) ? be : ! be;
                -- Wm. Shakespeare