BUGS:
Fix layering of nodes and edges
When a graph with no graphical information is loaded, then layout should be
	triggered.
If an executed model refs other files, then those files should be relative
	to the model, not to the cwd of the editor.
In TimedSource, attributeChanged triggers a fireAt().  What happens if
	an attribute changes before fireAt can be called?
Snap off port isn't accurate.
GraphControllers should be able to report errors in a systematic way.
Cancel close of InternalFrame doesn't work under jdk1.2.2  (use jdk1.3!)
Document event is never created for "no document selected"
Ports need locations.

TODO:
Text Annotation.
make newPort toolbar buttons draggable?
ptolemy modulation.xml -.modulation.something "..."
Snap to Grid.
Better Layout.
Title box on each graph.
Icon drawing app.
Improve debugger.
Instantiation by name.
Multiple vertexes per Relation.
Manager creation needs to get handled in one place.
improve ptolemy query/ parameter styles.
Need more control points for arcs in FSMNotation.
NoStoragePolicy for Applet
Persistence of user libraries.
Infinite Canvas.
reordering of parameters.
Explicitly describe what a well-formed model entails.

DONE:
Direct connections from Ports to Ports.
Layout breaks when toolbar gets dragged to the bottom.
Manhattan Routing.
Multiple Document Factories.
Visual Notations for Ptolemy Package.
Director specification.
Printing.
Better parameter configuration.
Exception reporting window doesn't grow vertically.
Mutation mechanism shouldn't always call wrapup.
SaveAs doesn't change model title.
Cut and Paste.
Changes to ptolemy model should be mutations and a changeListener should
set the dirty flag on the document.
Libraries shouldn't all be loaded at startup.
User addable libraries.