Compiz doesn't handle synthetic unmap notifies correctly

Binary package hint: compiz

See ICCCM section 4.1.4

"For compatibility with obsolete clients, window managers should trigger the transition to the Withdrawn state on the real UnmapNotify rather than waiting for the synthetic one. They should also trigger the transition if they receive a synthetic UnmapNotify on a window for which they have not yet received a real UnmapNotify ."

We are not treating the synthetic UnmapNotify any differently to the real one, so in effect compiz thinks the window is being unmapped twice. This is causing problems like invisible windows left behind (frame input windows) when windows are widthdrawn.