Strange Numpad behaviour on VNC

Yet another problem.

i watend to access my debian system via VNC –  so far so good.
The only Problem war: Why the f*** does the numpad not work as intended.

If i press 4 it deletes the first char and then writes a 4
if i press 7 it deletes the whole line and writes 7

so after googeling, it seems like, this is a known bug
(sorry i’m unable to find the reference here)

After some more googeling i found a nice solution: Using xmodmap

The Program should already be present on your system, if you have installed a default X11 environment.