"smart" apps from doing stupid things before they get MapNotify.
This avoids the recent Java+OracleInstaller strange problem too.
The patch may look huge, but it's only adding two KWin wrappers
for X(Un)GrabServer() and uncommenting the calls in Client::manage().
svn path=/trunk/kdebase/kwin/; revision=271152
plugin to check what the core supports, i.e. the opposite of supports().
Not used yet, but apparently will be needed e.g. for the new tranparency.
svn path=/trunk/kdebase/kwin/; revision=269291
