fbpanel supports fredesktop.org tray spec only. imho, kde apps use different protocol (at least old one).
So they should not show up - they are not supported.
But to be sure that it is not fbpanel's bug try gnome-panel or sfce4-panel - they both use fredesktop spec only.
I re-tried with 4.9 and get the same results. I cannot get KDE tray
icons to appear in fbpanel. Skype appears in the tray properly.
I copied the default configuration and re-tested, and it still would not work.
I tried rolling back to an earlier revision just to see if I was
insane, and ended up with 4.5, and the same results. Which says that
perhaps the KDE functionality just isn't there...
but since I still can't get blackbox working, I'm not sure how to test
this feature in fbpanel.
Are KDE tray icons working for anyone else? How would i get them
working for me?