Positioning a gdkmm window (in screen co-ordinates)

[John Emmas <johne53 tiscali co uk>]

Hi guys - for getting and setting the position of a gdkmm window we have 
Gdk::Window::get_position() and Gdk::Window::move().  However, if I'm 
reading the documentation correctly, these use co-ordinates that are 
relative to its parent window.  For getting a window's screen 
co-ordinates we can call Gdk::Window::get_origin().

I'm sure I'm just not seeing something - but what's the complementary 
function to Gdk::Window::get_origin()?  How can I position a gdkmm 
window using screen co-ordinates, rather than parent window 
co-ordinates?  Thanks.

John