Well, I misunderstood You and myself.
The idea to simulate the language hotkey works fine. If someone presess my registered hotkey, I`m sending the windows language hotkey to the program and the keyboard layout changes. It works fine.
But if I wan't to change the keyboard layout without the hotkey? Meaning not to change only one step forward but to change it directly to another keyboard layout. I`ve made that my program finds out what keyboard layout is using the program, but I can`t find out how to change it... Maybe there are some possibilities to call the
ActivateKeyboardLayout function to the active program?