This extension allows for a variety of things regarding taking screenshots of desktop - you can get a screenshot of entire desktop, or capture a part of it, or even get a screenshot of all displays on multi-monitor setups (particularly convenient if your game had been moved away from the primary screen).
Images of screen can be captured into surfaces (for drawing) and/or buffers (for storage/later recovery) - see doc for more information.
As such, this can be used for a variety of things:
Supported versions: GMS2 (GMS1 has an issue on some GPUs)
Supported platforms: Windows, Windows (YYC)
Source code included !