Double click the track will add a corner, we will remove the corner auto. Try it. :)

I have just tried this. We're sort of half way there. I can add corners by (i) Double clicking on a track; (ii) Move the end of a track which leaves the end point in place but adds new points to create a 90degree corner. (iii) I can remove a corner by moving a section of track if and only if the handle for that corner is *almost exactly* in a straight line between two other corners. If the line is not at an exact 0degrees, 45 degrees or 90 degrees angle then it can be very hard to move the middle handle so that it is in close enough to the straight line between the outer two. If the centre is not close enough to the straight line when the track is moved then the result can be that one end of the track being moved leaves the end point in place, creates new corners and the moved track rocketing off because an acute angle has been created. This is very hard to explain but easy to demonstrate in: `https://easyeda.com/file_view_near-in-line-corner_JnhztL3lC.htm` I think: (i) is very good. (ii) I am not sure about this because it adds 90degree corners even when the user has selected 45degree corners. (iii) this makes it hard and confusing to remove corners. If this can be done even if the middle corner is a long way off being in a straight line then maybe that would be OK. It would be much better if the green corner handle could just be selected and simply deleted. Maybe that is not possible yet ... :)