This shouldn't happen on a well UV-mapped, manifold mesh -- well, unless someone manages to click exactly on one of the triangle corners. Better to get this fixed now then to run into floating point shenanigans later.
part of CURA-12543
Refactoring that part to up top caused the problem I think -- getSelectedObject(0) over getAllSelectedObjects()[0] is clearly the better call in this case anyway.
part of CURA-12543
The most important thing to make it work is actually notifying the scene that something has changed -- the rest are just refactorings and (hopefully) optimizations.
part of CURA-12543
Also typing. The way it now works is way too slow though, and it doesn't add 'inbetween' the moude-move-positions yet. Also several other things of course.
part of CURA-12543
Should be able to paint pixels now if the tools is active, and the model loaded is with UV-coords (that rules out our current impl. of 3MF at the moment -- use OBJ instead), and you position the model outside of the build-plate so the paint-shadr that is temporarily replacing the 'disabled' one is showing.
Will need a lot of extra features and optimizations still!
part of CURA-12543
