set-value in slider%
Sets the value (and displayed position) of the slider. (The control's callback procedure is not invoked.)
A slider's value can be changed by the user clicking the control, and such changes do not go through this method; use the control callback procedure (provided as an initialization argument) to monitor value changes.
( -> void
send a-slider set-value value)
value : exact integer in [-10000, 10000]
If value is outside the slider's minimum and maximum range,
an exn:application:mismatch exception is raised.