The design of "touchy"[1] is as follows:

No keyboard is required.

No mouse is required.  It is meant to be used with a touch screen.

Configurability of font sizes makes it work with any screen
resolution.

Some hard controls are required.  The absolute minimum set of
controls is:

* A momentary abort button, connected to the hal pin touchy.abort

* A momentary cycle start button, connected to touchy.cycle-start

* A wheel/mpg, connected to touchy.wheel-counts

* A single block toggle switch, connected to touchy.single-block

* Of course, a real estop button hardwired in the estop chain
  as usual (not strictly related to touchy)

Additionally, there are some optional controls:

* If continuous jog is wanted: Three center-off bidirectional
  momentary toggles (or worse, six buttons), hooked to 
  touchy.jog.continuous.x.negative, ....x.positive,
  ... y ...,
  ... z ...

* If a quill up button is wanted (to jog Z to the top of travel at
  top speed), a momentary button connected to touchy.quill-up

There is currently one optional indicator output:

* touchy.jog.active can be connected to a panel lamp to show when
  the panel jogging controls are live

Touchy has several output pins that are meant to be connected to
the motion controller to control wheel jogging.  They are:

touchy.jog.wheel.increment => axis.N.jog-scale (for all relevant N)
touchy.jog.wheel.x => axis.0.jog-enable
... y ... => ... 1 ...,
... z ...

Also be sure to connect the wheel/mpg to axis.N.jog-counts as well as
to touchy.wheel-counts.  If you use ilowpass to smooth wheel jogging,
be sure to smooth only axis.N.jog-counts and not touchy.wheel-counts.

Touchy requires you to write a file named "touchy.hal" to make
these connections.  Touchy executes the hal commands in this file
after it has made its pins available for connection.

These things should be done some day:

* continuous jog inputs, from two buttons or a center-off
  bidirectional momentary toggle switch, that jog the currently 
  selected axis.  On a many-axis machine, separate controls could 
  get unwieldy, and this would be a good compromise.

These things are not done, and may or may not ever be done:

* direct viewing and editing of tool table.  

  I currently use a network connection for this, just like I use
  network to edit/replace the gcode programs.  G10 L1/L10 is good
  enough for the normal tasks.

* Calculation and display of the extents of the loaded program

  This requires interpreting the entire program, and is a bit hard
  to get right because of tool lengths and other considerations
  like probing.


These things will never be done, don't ask:

* Add onscreen controls for jogging and cycle start, etc, so
  touchy can be used without real controls on a real panel

  The reason for this is the unreliability of touch screens and
  the safety that comes from having actual buttons/switches/wheel
  to do dangerous and critical operations such as executing gcode
  or jogging.  Even with MDI you must use the real button, after
  confirming the command displayed onscreen is what you want.
  This is a feature.

  (It is possible that homing and spindle fwd/rev should also
  require a press of the cycle start button for safety's sake.
  They currently do not.)

  I have seen two controls that attempt to allow you to jog using
  a mouse or touchscreen.  On one you drag your finger/pointer in
  a circle.  On the other, you drag it from side to side.  These
  work very badly and touchy will not have a scheme like this.

* adding a full onscreen keyboard for any reason

  These suck.


[1] Like "git", "touchy" is named after its author.