9/99 Button Scheme for CONTROL

    The button array for the CONTROL program (LOAD, CANCEL, START, et al) has
been changed.  All the buttons are momentary now (i.e., none of them stick
down).  In this way, one can have any number of button arrays without having
conflicts between them because some had a button stuck down and another didn't.
In fact we've now implemented buttons on the Frankenheim terminal that can
be pressed with the mouse.  If this proves popular, we might relocate the
real buttons to one of the receiver rooms.

    And since one is not limited to the above two arrays, we plan to set up
another one in Tucson when we test out remote observing.  (We'll also have to
work out a scheme such that virtual buttons can't be used without the Mt Graham
observer's permission.) 

    The operation of the buttons is now slightly different.  For the one's that
used to stick down, one now presses them once to enable them (indicated by
the lamp coming on) and again to disable them (the lamp goes off).  This is
fine except for START, WAIT, and AUTO.  In the old scheme, their lights didn't
come on until their function was active.  Now, they must be turned on/off as
soon as they are pressed.  So three extra lamps were implemented (STARTING,
WAITING, and IN AUTO) to indicate when these are not just enabled, but are in
fact active.  For example, when START is pressed, the START light immediately
is turned on or off, as appropriate.  When it is on and a subscan actually
starts, the old START lamp would have been turned on.  Now the STARTING lamp
comes on too.

    Finally, the positions of the buttons have been rearranged.  The two most
frequently pressed, LOAD and CANCEL, are now on the end where they can be
more easily found.  Next to them are START & STARTING and WAIT & WAITING.
The remaining buttons are seldom changed.  Their positions were chosen in 
an attempt to group like functions together.

    Note that CONTROL only checks the real buttons 4 times a second.  So they
must be held down at least a quarter of a second in order to be sure that
CONTROL will notice the press.  This is NOT necessary for the virtual buttons.