While being a great and promising idea for a tool, it's with regret that I reject this tool, because of the following reasons:
1) If you try to delete a frame that is already used in any animation, a Null Pointer Exception is yielded, thus causing errors;
2) The tool's actions are not being properly saved in the corresponding project files (*.dyz).
It's a pity, the tool is certainly a good improvement in the art of sprite designing. Also, some PIXI compatibility would be nice at this point.
EDIT: the author provided this download link
for all the users that would like to test the various features the tool offers.