I should be more specific. Try
m1 clipSubmorphs: true.
Hope that helps. David
p.s. I think your do loop pre-empts the Morphic UI loop. Have you read John Maloney's tutorial on the step method? http://stephane.ducasse.free.fr/FreeBooks/CollectiveNBlueBook/morphic.final.... In the meantime, you could switch your Transcript hack for this hack :) m1 refreshWorld.