Fluxbox

Having a window switch desktops by disappearing and reappearing lets the
window get lost. It is still there but invisible and can be forced to
reappear with a xmap request,

This especially occurred when trying to summon an open chat window to
another desktop with the psi instant messenger. For further info and a test
case see: http://flyspray.psi-im.org/task/952#comment1024