system tray doesn't resize properly when changing panel position

Binary package hint: kdebase

I'am using Kubuntu Dapper Drake and I have a following issue (which I remember also from Breezy): when changing panel's position from horizontal to vertical system tray doesn't resize properly and applets draw themselves in a way that they are partially hidden. My panel is fairly thin, maybe it is because of that? But when I restart KDE with panel in vertical postion, then applets get a hint and draw themselves ok. Then again, it is enough to move panel to horizotal position and back to vertical, to break things again (until next restart).