Comment 16 for bug 237731

Maximus seems to be the problem. I set it to undecorate, to have Window Buttons in the panel, and the panel becomes invisible when I close a maximized window. Firefox and Thunderbird are not affected, I have the problem with Nautilus, Terminal and more than anything else with Synaptic. As soon as I turned off the undecorating in the configuration editor, the problems disappeared.

OpenBox can be set to undecorate, but that's not an alternative for me, because it shows the window buttons in unmaximized windows to the right, like Windows. The natural place for the Panel Buttons is to the left, so it would be a bit confusing...