I am hitting this bug: NEWT errors when closing sketch on Linux  Issue #1651  processing/processing  GitHub, when using Processing on Linux (Ubuntu 11.04); my messages are:X11Util.Display: Shutdown (JVM shutdown: true, open (no close attempt): 1/1, reusable (open, marked uncloseable): 0, pending (open in creation order): 1)X11Util: Open X11 Display Connections: 1X11Util: Open[0]: NamedX11Display[:0.0, 0xa3b8aa8, refCount 1, unCloseable false]Finished.The problem is, if I start a Processing program after that, it will usually lock (start with a blank screen); and then I have to re-start again. So I wanted to go according to the error messages, and try listing these Open X11 Display Connections or NamedX11Displays on a live system, so I could close them. But it turns out, I have no idea what command tool, if any, to use for this purpose. (Btw, those messages are apparently from the Java jogl library). Is there such a tool, that would query the live state of X11 (as a whole) on a system, and list all open displays and connections? How could I proceed to close one, if the originating process (e.g. processing) has already exited the process list?
List/query Open X11 Display Connections?
command line;x11;utilities