This question seeks additional data for issue #2744. There, you had recommended using basic shapes in place of the thick lines required to depict the Fork and Join nodes.
I have a similar application for argument maps:
The join shape is needed to depict Dependent premises or co-premises. (see here).
The Fork shape is needed to connect a given node to multiple other nodes. (Often we re-use a given premise to support multiple conclusions.)
In my application, I will not need swim lanes. So this is a simple case of being able to use connectors (edges) correctly.
Well, I can definitely make a rectanglular shape thing enough to resemble a thick line. But when it comes to connecting edges to this shape, I want to make sure that only the "broad" sides of this shape get connected: The "thin" sides of the shape must not get connected with incoming or outgoing edges.
In other words, the glue-points for edges must lie on the "width" sides of the shape, and not on the "thickness" side of the shape.
And this should happen consistently, regardless of the orientation of the shape (I should be able to make it horizontal or vertical).
What should I do to achive this?