diagram-editor

Metamodelling tools..

What tools are available for metamodelling? Especially for developing diagram editors, at the moment trying out Eclipse GMF Wondering what other options are out there? Any comparison available? ...

How do you develop an application to draw, edit and save UML models in Cocoa?

Will the individual UML diagram shapes be NSView subclasses or NSBezierPaths? How are the diagrams created and managed? ...