First, thank you for a very powerful component. It is obvious that it took much work and creativity to create it. In the interest of providing you with field information about your component, I am reporting a small bug: Whenever a user places a Link/Line that is not directly over a previously created node, the control throws an access violaton. The easiest way to reproduce this is to attempt to place a Link/Line on a blank SimpleGraph canvas. This seems to be in the "SetCommandMode" procedure.
I am using D5 running under Win2K.
Best regards and thanks again for some great components for the Delphi community!