Resources for the [[http://eclipse.org/gef|GEF]] Plugin for Eclipse
GEF = Graphical Editing Framework
Probably the best source about GEF seems to be simply the online help. The demo programs are nice. You should understand the meaning of the LightweightSystem early, so that this class does not irritate you.
Here are some of the interesting links where we can find examples (works with eclipse 2.x)