I've tryed the 4.1.10 version on win7, and I found that don't allow me to load clips with non standar characters in his filename (á,é,ô, etc). On the same system, v4.1.8 load the clips without any trouble. Then I've tryed the same version on another windows installation and worked fine, as usual. An...
Is nice for some simple situations. Can be a good fixer.
The point is, if you work on some serious mapping, you can´t handle dozens of non square masks.
Render and correcting by slicing is still your best shoot.