Thank you,
I'm able to focus an element and enter values. But yet I didn't manage to unfocus it: I have to press Enter or Shift+Enter respectively before focusing another. Therofore I tried to feed those keys back, but Enter, F2, ... have ChrNr. 0 and it seems impossible to feed back scancodes.
My preliminary programms are in the attachments. I don't know wy I have to place the controls (just a string and a number) inside the event box.