Transparency using RGB

[Andy Bell <andy bell allbabel com>]

Hi All,

I am trying to create a transparent GtkWindow using a RGB colour space.  I know I can use the RGBA colour space to do this but I am restricted with an RGB one for the moment.  I want to be able to create the transparent effect by first taking an RGB pixmap of what is behind the GtkWindow and then drawing content on top of this pixmap to give a transparent effect to the Window.  Does anyone have any ideas on how I can get at the pixmap data of what is behind the GtkWindow?

Thanks in advance

Andy