MouseKeys randomly stops working

[Richard KLINDA]

Hello, I've noticed a strange bug, I suspect (am not sure) that X.org is
the culprit.

Here is the bug report from the Debian bug tracking system:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=463363

Summary: when I turn on MouseKeys it works, but after some time (5-20
minutes) it stops working.

Does anyone know anything about this?  Is it a known thing?

Thanks in advance,
Richard