-------------------------------------------
entry variable: $shrinkcycles -- cycles of redraws
-------------------------------------------
default: 10

The "cyc" entry (F3 panel, middle bottom)
controls the number of times the C/tcl function,
shrink(), is called.  Each call passes
$shrink_steps to the function, so the total
number of passes thru the inner loop of the
function will be:

  $shrinkcycles * $shrinksteps

The surface will be redrawn once after each cycle
(once per shrink() function call).

Here is an example of how to run shrink from a
tcl script, and write a numbered tiff of each
shrink cycle output into the subject's rgb dir:

set steps 10
set cycles 100
for {set cyc 0} {$cyc < $cycles} {incr cyc} {
  shrink $steps
  normalize_area  ;# optional
  redraw
  setfile rgb ~/rgb/frame-[format "%05d" $cyc].tiff
  save_rgb
}
