Version: 4.0.83 (using Devel) Installed from: Compiled sources Start KDE, and launch some Firefox 2.0.0.14 windows. Then in System Settings activate desktop effects. As soon as the desktop effects are applied, the Firefox window disappears on the screen. It is still in the task bar, and with the cover switch plug-in I can see it is still running, but it is not shown when I select it in the cover switch task switcher or in the task bar on the panel. When I disable desktop effects, the Firefox window becomes visible again.
*** This bug has been marked as a duplicate of 160393 ***