Version:            (using KDE 4.2.2)
OS:                Linux
Installed from:    Ubuntu Packages

This is a default KDE (from Kubuntu Jaunty) installation.

When a window has _NET_WM_STATE_SKIP_TASKBAR set, not only should it not show on the taskbar, but it should be hidden from the ALT+TAB window list as well.  This way, an application that wants to hide without any trickery can do so by simply setting _NET_WM_STATE_SKIP_TASKBAR and minimizing itself.  Such applications that would want to do this are, for example, applications that dock in a tray or have a keyboard shortcut.  This makes it easier than trying to map or unmap, and when honored, is a cross-DE method of removing the window from circulation in the stack for keyboard window switching.

Currently, KDE does not hide it, breaking the expectation that the window is removed from view entirely.  This affects the current application-centric development tree for AllTray, which now no longer works on KDE.

(I'd prefer to avoid having DE-specific methods for accomplishing this, obviously.  Skipping the task bar should remove the window from the window list, and other methods such as those implemented by classic AllTray do not consistently nor reliably work because it breaks standards left and right.  I am working to correct this, now that the relevant standards are out and have been for some time.  That said, if there is a KDE-specific trick that can be used for KDE 4, I'd appreciate learning of it.  If KDE 3 requires some trick to accomplish this, I'd like to know of that, too.)