I wrote a software in pascal.
it "zoom switcher" - a mac os expose like application
("http://www.grg-software.com/")
However, while writting it, i noticed that the PrintWindow win32 functions has problems with getting a snapshow of the desktop - in case there is a wallpaper, it is not included in the snapshot, but instead the background is black
i found other win32 apis to also have strange behaviour

be carefull with api functions, they have an suspicious behavior, and you can get various errors on different OS systems. also i can not find the PrintWindow in api.

try to use the VCL, the drawing routines, instead of using API functions.

also provide the errors you encounter.

best regards,