Does anybody know how can I catch some keydown event with a background apps?
I try all of publicated library but I found only a way when my app window on focus.
If you're making a keylogger (which you hopefully aren't), ...
It's not possible to catch keystrokes in other windows.
If you're making a keylogger (which you hopefully aren't), you can try continuous screengrabs, clipboard monitoring or "form grabbing".