Comment 3 for bug 459290

The cause of this was found by SnailCZ on the forums:

Update:
I found solution.
Set your application font-size to something that's not using a fractional part. For example if you have set your main
application font-size to 7.5 set it to either 7.0 or 8.0

Reference: http://ubuntuforums.org/showpost.php?p=8153267&postcount=2