When I right click on an EPUB and select Open With and choose Ace, the Ace App opens but does not start processing the EPUB. I must go back to the EPUB and drag it into the App.
However, if the DAISY Ace is already running and waiting for an EPUB to be dragged into it, then right clicking on the EPUB and Open With ACE does work as expected and processes the EPUB without having to drag it into the app.
This was on Windows (Intel) 1.3.5.