draw.io started life as one of the examples for mxGraph [1] and we've got a pile of stubly different behaviours available, it's just extremely tricky to expose any great number of without making the UI crap.

Do you mean something like [2]?

[1] http://jgraph.github.io/mxgraph/javascript/index.html

[2] http://jgraph.github.io/mxgraph/javascript/examples/wires.ht...