That's a true KDE PIM Operating on an invitation in the KMail part in Kontact triggers a calendar update in the KOrganizer part while being hidden causing the splitter synchronizer event filter installation to fail randomly for some splitters of the side-by-side view resulting in a totally messed up view after switching back to KOrganizer. Of course only when using side-by-side view exclusively, not in the tabbed mode.

No idea how to really fix this, so as a workaround update the view again after being shown if the above problem was detected while being hidden.

Kolab issue 2675