[ZeroGravitas]

I think there's a bug here, maybe only some people are seeing it.

You're describing the UI for drawing/connecting the lines (optionally with arrows) which is very nice. What's strange is that every other shape if you click on it produced an item in the top left which you can drag to the required position and size. But, at least for me, the lines don't do this, you need to drag from the palette onto the screen then drag the ends onto boxes or where you want them. Seems strange to me.