Author: Jonas Bilinkevicius
How to hook into Windows' built-in screenshot function

Answer:

1   { ... }
2   if not fullScreen then
3     Keybd_Event(VK_MENU, 0, 0, 0);
4   Keybd_Event(VK_SNAPSHOT, 0, 0, 0);
5   Keybd_Event(VK_SNAPSHOT, 0, KEYEVENTF_KEYUP, 0);
6   if not fullScreen then
7     Keybd_Event(VK_MENU, 0, KEYEVENTF_KEYUP, 0);
8   { ... }


The fullScreen value tells, if you wish to get a windowed printscreen or the full screen.