Samy with it's sharp eye noticed that mirror line/point may not only mirror, but create wrong shape. The reason is because the old code used directly the shape's transformation instead of using OpenCascade's MakeEvolve API.
This is annoying when some other operations (mostly Boolean operations) appear to work randomly.
So the code for Mirror actions (excluding mirror plane, I'll may finish tomorrow) is fixed.
Expression evaluator was set up in missing points in property grid (for setting X/Y/Z coordinates).
Also TreeView's usages were hardened, by looking to most cases when extra tree view work was involved instead of minimal updates.
Solver code will have have precomputed parallel axises even you disable the parallel lines.
The last two changes will make the future release a bit even snappier so I already wait to see it.