Font problem in 8.10

[jis]

I couldn't log out due to this:
http://ubuntuforums.org/showthread.php?t=406356
So I cleared the cache and rebooted like told in the last post.
Now fonts are bad size. How do you change font size used in xfce4-panel and its items? xfce-setting-show seems to use smaller font than the panels and applications..

[jis]

I got font sized more uniform after I changed Font DPI setting in User Interface Preferences from System Default to something else. How can you fix the "System Default" Font DPI setting to produce uniform font sizes?