The new Code Bubble IDE has been in the news. I wonder if there are useful libraries to implement this kind of interface (for other applications)? I prefer java or python. I understand Code Bubble has been implemented on Eclipse.
It looks more like it's implemented in Squeak Smalltalk using it's interface parts as building blocks and Eclipse as back-end.
You can use some sort of good custom drawing library like Piccolo http://www.piccolo2d.org to build your own blocks and connected them together.