I'm not good with a mouse, so I found it hard to edit animation lines.
The mouse position has to be quite precise, with only a small threshold.
Looking at the code, AutomationLine sets the threshold for the PolyLine
to 4.0 . That seems to be a distance, and better for me than what I
experience.
The actual code in PolyLine is however comparing it directly to the
squared distance, making it more sensitive than expected.
Fixed by computing the squared threshold - also including the line
width.
0b27d6e652