transparent toplevel window on gtk on DirectFB

[david a gamache l-3com com]

I am going to target
glib 2.24.2
gtk+ 2.24 
running with DirectFB 1.4 on an embedded system.

I want the toplevel window to be transparent and things that I draw on the drawing area (using cairo) to be 
on top of what is being displayed directly on the LCD.  My hope is that the frame buffer elements with 
transparent toplevel window will allow what is being displayed on /dev/video1 underneath to be seen.

I was wondering if my glib/gtk/directFB set-up provides me with what is required to take the approach 
described here:
http://library.gnome.org/devel/gtk/2.24/gtk-question-index.html#id588786

It's not clear to me.  If there is another method more likely to succeed, please let me know.

Thank you,
David