While testing and studying the Network Model in Mason Tutorial 5, I 
find that although the "SimplePortrayal2D" class could be extended to draw 
the Network Nodes in a "ContinuousPortrayal2D" Field, the Nodes seem not 
to be movable by mouse drag when the model is being paused.

     Is there a way to modify Tutorial 5 so that, when the model is being 
paused, I could drag a Node to move it around while the Node's edges would 
redraw themselves to reflect the Node's updated location ? 

     Thanks for any suggestion.

Lawrence Tsang