Printing and sound do not work properly as it is (sound is unreliable and unsafe - printing does not work on win32..) So just disable the options until we sort this out.

All session types should have a startup timeout which will check that the session has moved past "starting" state within 30 seconds. Some do, but not all apparently (or at least not in all cases). At least we now detect SSH errors and report them to the client.

In most cases the racy code is harmless, but in some cases (preload sessions) a user could end up having access to someone else's session! Must add the equivalent of Java's synchronized keyword to quite a few places...