Created attachment 62598 [details]
Screenshot of the problem when occurs

Version:           unspecified (using KDE 4.7.0) 
OS:                Linux

The task manager sometimes seems to be confused about the number of tasks that are running, it leaves a gap between tasks. eg. [task 1][task 2][     ][task 3][task 4]. It also doesn't respect its settings sometimes, eg. set to max rows of 1, but it still uses 2 rows. See the attached screenshot.

While this happens on one of my virtual desktops, it doesn't happen on others. It can happen to all virtual desktops, just not any particular one, this is quite random.

Reproducible: Sometimes

Steps to Reproduce:
I'm currently unsure of the exact steps to reproduce this, but it happens farely often. But here are some steps that may or may not reproduce this. Note I have set the task manager to display only tasks from the current desktop, but once the problem happens, setting this option on or off doesn't matter anymore.
- drag a task from the task manager to another virtual desktop by dropping it on the pager widget, or
- simply switch from one virtual desktop to another, or
- a combination of both described above


Expected Results:  
Do not leave any gap in the task list and respect its settings.