Event loop button functions
        These buttons control the event loop operation.  Here the blue buttons control event by event displays.  (9/17) These now just turn on the displays for the corresponding tasks, but in future they may bring up a separate panel to choose the display type and alter parameters.  The aqua color buttons allow you to start/stop a delay loop pause during which no new events are brought in and you may change from one type of display to another.  Displays are refreshed even if not altered whenever any panel button is clicked.  Display settings during a pause will affect future event by event displays after a pause, and display parameters may be changed "on the fly".  STOP ends the event loop in the same way as if the number of events were set to the current total.  HELP functions as during initialization.