> The idea is to have (for each redraw) the display method stop
> after a given elapsed time so that the Morph does not slow
> down everything. Later on I'll be caching intermediary results
> so that the Morph will indeed be completely redrawn at some
> point, but at the moment I'm just trying to
> have it stop displaying, and I can't succeed.
The best way to do it is to use a form for caching the bits you want
to see. E.g., something where your drawOn: method just looks like:
    aCanvas drawImage: displayCache on: bounds origin.
Then, you can use the step method, a forked process or whatever more
to draw whatever you want to do on the displayCache.
> what am I missing here ?
Probably some weird complex interaction. Try the above - it's much
simpler to use and to understand.
Cheers,
  - A