Usage is simple: given a Window, present() it, and then call the capture method here.

 final Window window;
 final Pixbuf result;
 
 window.present();
 result = Screenshot.capture();
 result.save(...);
 

Note that for some reason taking screenshots is a very slow and CPU intensive process. Unfortunately, it occurs within the GDK lock and thus will block your UI for a few seconds. Threading can't help you parallelize this.

LICENCE WARNING
This native code used to take screenshots is licenced under the GNU General Public Licence, version 2. As a result, use of this class in an application will mean that entire application will need to be available under a GPL v2 compatible licence.