That was quick work.
The leads seem to work very well, it took me a long time to figure out that a lead would not appear until the start point was manually set. I would think that having them applied at the starr if they are enabled would be ok. I did try it with these lines commented out and it seemed to work without issue.
Code:
# if not polyline.start:
# # only if a start point is set
# lead_in_active = "off"
# lead_out_active = "off"
I did a quick video of my mouse issue trying to set the start points.