[ProcessController] Some menu entries are removed and become white when lots of processes are running

[oco]

The problem start when all processes do not fit on the screen (menu too high).

To show the problem, you should use something that create and destroy a lot of processes like building something (building Haiku for example).

While showing memory or CPU menu in Process Controller, some white entries appear and replace progressively all entries.

Tested in hrev42926.

See attached screen shot.