Undo and half-turn metric

[thomas-lehericy]

I'm using MagicTile_v2_09-29-16 . This problem is recurring in all three puzzles in the "start here" section : the rubik's cube, the torus rubik, the klein bottle and the hyperbolic rubik. I conjecture it still holds for the other puzzles.

When doing a move or a face, then undoing it by turning it in the other direction, the software counts two moves, but this sequence has no effect whatsoever on the puzzle. While this is coherent with a "no-cancellation" style of solving, there is a ctrl+z button that contradicts this philosophy... It would be interesting to make such a succession of move cancel itself instead of counting two.

A sub-issue would be to be able to use the "half-turn" metric : every sequence of turns of the same face (++-+-+++...) counts one turn if the state of the puzzle is different after and before the sequence, and zero if it is the same.