Comment #4 on issue 842 by google....(a)ben.coman.com.au: ROTranslatingShape
mouse hotspot mis-alignment
http://code.google.com/p/moose-technology/issues/detail?id=842
Perhaps needing more consideration, previously the children were always
drawn last and ended up on top of any shapes, whereas now they get drawn
first and _might_ be overwritten by a later shape of the parent.
Perhaps we need to be able to arrange the ROChildrenShape into the middle
of the shape-chain.
Or perhaps drawing children is special and done differently to the rest of
the shapes, so that it is always drawn last but not affected by
ROTranslateShape.
Perhaps something roughly like....
ROAbstractElement>>drawOn: aCanvas
shape chainedDrawOn: aCanvas for: self
ROChildrenShape new drawOn: aCanvas for: self.