I started by using Windows Task Manager to try to find the 'hanging' problem, and after sorting the process list by CPU usage - there was 'cat' spinning away. Process Explorer v9.02 provided the same data. Trying to 'cat /proc/PIDNO/cmdline' would only provide "<defunct>".
It does not matter if I use 'rootless' or 'multiwindow' - X stops at the "Rules" line (although I often see a clipboard connection message).