I have a fairly large java application which is partly made up of a
whiteboard which you can use a freehand tool to draw on. Currently it
works by simply listening to mouse movements and recording each point
etc.
  This works fine unless some other thread is already going when
theyuser tries to start drawing or decideds to run (even at a low
priority) when freehand drawing is in place.  I CANNOT afford even a
small delay in handeling user drawing as mouse movement is lost and
the lines drawn look funny.
  So basically as soon as the user starts drawing (mouse down) I want
to lock all other threads so I am only catching mouse movements (even
if I have to get the AWTEvent from the EventQueue directly) and call
paint on the graphics object to update the screen for that line
segment. Then when the uses stops drawing the line (mouse up),
reenable all the other threads.
 
 However, given I don't have control over some of the other threads
codebase (some are written by others and some core to java -- like gc)
the only way I could come up with was to enumerate all the threads
(get the highest ThreadGroup parent) and suspend() all those that are
not me. However, this could possible cause a deadlock.

 Anyone have any other ideas about how to fix this?

  Thanks,
       Preston