Version:           unspecified (using KDE 4.7.0) 
OS:                Linux

After some time of use (a hour or little bit more) there some spaces appears in the taskbar. I've attached screenshot. Taskbar is configured for using in one line, but it start ordering buttons in 2 lines, even if amount of open widows is few.

Reproducible: Always

Steps to Reproduce:
Just regular using. Open windows, close, switch desktops.

Actual Results:  
Wrong button ordering, ugly spaces appears.

Expected Results:  
One-line button ordering. No spaces between buttons.

I can manual reorder buttons, but spaces between buttons are steel exist, there is no way to remove they.

Ubuntu 11.04, x86_64, One display, 6 virtual desktops, Intel graphics, desktop effects are disabled.