I set up a "Sort by" button in the Dolphin Toolbar with an self-configured icon because this button does not have an icon by default.
So it looked like this:
http://wstaw.org/m/2012/04/19/sort_by_button.png

After a restart of dolphin the icon was missing and it looked like this:
http://wstaw.org/m/2012/04/19/shadow_bug1.png

I tried the same thing with other toolbars at other applications but it only happened at dolphin with the "Sort by" button.

Reproducible: Always

Steps to Reproduce:
1.Set up a "Sort by" button at the dolphin toolbar with an icon
2.Restart Dolphin
Actual Results:  
The self-configures icon was gone

Expected Results:  
There should be an icon

This bug only occurred at the "Sort by" button for me. I tried it with other buttons and it worked fine.