We said MASON wasn't guaranteed to be backward compatible during its
prerelease mode and we meant it!  :-)  We've made lots of changes,
especially to the Java3D code.  But the four which will affect you 
the most are:

0. The first time tick of Schedule is no longer 0.  It is 1.  Thus you
can't schedule things for time 0, and as the Schedule simply returns null
when you try to do so, this can result in all sorts of odd results.  The
best thing to do is to schedule things for Schedule.EPOCH, which is a 
constant (set to 1).

1. Bag is now a Collection.  Accordingly we've renamed some Bag methods:
Bag.addObject(..) etc. is now Bag.add(...), etc.

2. The Java3D code has been heavily overhauled and revised.  There are so 
many changes here that probably the best thing to do is to go through the 
two new tutorials and get a handle on how the new system works.

3. We've renamed ValueGrid2DPortrayal to ValueGridPortrayal2D,
Continuous2DPortrayal to ContinuousPortrayal2D, etc.  Similar renamings
have occured for the 3D portrayals.  One easy way to convert your code
is to use the convert script (which relies on the convert_h script in its
own directory), which will do all the renaming inside java and html files.
The renamings are restricted to field portrayals.  For a full list of the
renamed portrayals, see the CHANGES file.

Additionally it might be worthwhile to examine the new tutorials to see
minor changes in how we suggest writing the code.

If you have any trouble upgrading, try contacting Sean Luke at
sean@cs.gmu.edu
