Hi there 
actually it was something I was playing a lot in the past, I came to the conclusion that the line algorithm used in most programs (including Aseprite now) is the best one (?) to draw continuous lines (e.g. the regular freehand stroke, or one line after the other). (Where the starting error of the Bresenham algorithm depends on the width+height of the line instead of starting in 0).
I think we need some kind of switch to use perfect lines or not in these cases.
A comment about the current line algorithm in the code:
// Useful to create continuous lines (you can draw from one point to
// another, and continue from that point to another in the same
// angle and the line will look continous).
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