Boolean Difference/Exclude operation got broken

[devviktoria]

If I create a boolean Difference/Exclude operation on 2 shapes the intersecting part is still visible, however it should not be.

normalboolwrong-2026-09-08_13.47.00.mp4

(f I observed correctly the point and segment data is generated correctly for the result, but the display is still wrong.)

[0HyperCube]

A regression from #4463/#4464 (where the author seemingly didn't really test their code and completely skipped code reviews).

There are many other easy to discover failure cases e.g. boolean subtracting the ellipse from the rectangle (both filled with red):

• Sometimes a corner is missing fill
• Sometimes the whole thing doesn't have any fill
• Sometimes only one corner is filled