Thanks for the link, this helps.

But I don't need it to be planar, that was introduced by the discussion.

> Looking forward to finding out your final strategy for getting it onto a screen.

I just realized again that my clients don't really know what they want, they've seen different pictures with boxes and arrows and agree to like it.

Unfortunately different stakeholders have shown me diagrams with very different semantics and aim now.

My fall back scenario is to turn a Gantt chart up-down and draw the boxes at the start of the bars.

This would mean the source is on the top-left and the sink on the bottom-right

Probably I can try and move lower boxes into empty left space to have it more top down.