Copy Houdini :)

[virtualritz]

Houdini is probably the app to look at, as an example, what to implement for a node graph editor. They've been around the longest. TouchDesigner is btw a fork of Houdini. It's long enough ago they may also have added some novel ideas but I wouldn't know.

You can download and play arround with Houdini for free (Apprentice version).

Stuff of the top of my head:

• (Grid) snapping
• Comments
• Underlying nodes with a named, colored rectangle (that stays)
• Layouts
• Adding vertices to connections to make stuff clearer/disentangle
• Coloring nodes/vertices/edges of a graph
• Changing node shapes

I suggest watching this video for some inspiration.