Version:           unspecified (using KDE 4.7.0) 
OS:                Linux

After last upgrade to KDE 4.7.0, the Tasks Panel (or tasks manager panel/bar) has become a real pain, fully unusable (it worked perfectly before).

I've it configured to force a single line ("Maximun number of files: 1").

At any time, when I open a new app I see random empty spaces in the task panel (so for example I have two apps open and I see the first one on the panel left and the second one at the right or wherever, by leaving empty spaces between them). Also, I open more apps and the panel becomes a two files panel (again with multiple ugly spaces inside).

Even worse, sometimes I change the active virtual desktop and the tasks panel still shows the apps in the previous virtual desktop (note that I use "Just show tasks in current desktop" enabled).

Note: I don't use different Activities and so.

As said above, I've been using the same configuration for years and it never failed. This must be a clear bug in last upgrade.

Reproducible: Always

Steps to Reproduce:
Configure the tasks panel as follows (translating from Spanish):

- Force file preferences:  false
- Show advises:  true
- Highlight window:  false
- Maximun number of files: 1

- Grouping:  Don't group
- Ordering:  Manually

- Show just tasks in current screen:  false
- Show just tasks in current desktop:  true
- Show just tasks in current activity:  false
- Show just minimized tasks:  false

Configure more than one virtual desktop and start opening apps and changing from a virtual desktop to another.

Actual Results:  
Taksbar becomes ugly, with lot of spaces between tasks and, sometimes, using two files rather than one. Sometimes displayed tasks belong to other virtual desktop.

Expected Results:  
Run fine as before.