In the latest moose dev image: 

http://hudson.moosetechnology.org/job/moose-latest-dev/lastSuccessfulBuild/artifact/moose/moose.image

If you create a model and try to visualize  system complexity from all classes, an error will be thrown:
  MOTreeLayout(Object)>>doesNotUnderstand: #topGap:

I guess it is due to some modifications in mondrian and that the code of system complexity has not been updated.

I opened and issue: http://code.google.com/p/moose-technology/issues/detail?id=496