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entry variable: $shrinksteps -- steps per redraw
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default: 2

The "steps:" entry (F3 panel, middle bottom)
controls the number of execution steps
(iterations) passed to the C/tcl function,
shrink, for each cycle.

The surface is redrawn once each cycle (function
call), so to see results of every pass through
the inner loop of shrink(), set this to 1.
