I have a system which runs for a long time, even though it is in standby some time of it, and the system monitor is usually running  all the time.
After a day or so system monitor show tasks which doesn't exist anymore because they have already been closed.
They don't have a high memory usage but if I use ps to check for them they are not there and if I restart system monitor they are gone too.
So there seems to be a problem in system monitor to remove some finished tasks.

Reproducible: Always

Steps to Reproduce:
1.run system monitor
2.let it run for ~24 hours - probably start and close some application in this time
3.compare the tasks in system monitor with the one of ps
Actual Results:  
system monitor shows tasks which are not there anymore

Expected Results:  
system monitor should only show existing tasks