Comment 7 for bug 1245339

Hopefully fixed again.
The latest change solved the non-declared bug where you change the original of a clone of layer when it's in a group whose transform is not commutative with the layer's, because i messed up a non-commutative matrix multiplication (example : take an object, clone it, put the original in a group, move the group, enter the group, change the object of layer; the clone moved... Not anymore with this new patch).

Taking a paper and pen helped :) .