Some time ago I saw a post in which said that only runs only in Windows, is that yet.
It is still windows only and will be for a while longer. Fortunately the framework FOR the designer is completely platform agnostic and we took quite a bit of effort to design it well, our design on Windows makes use of some native functionality to provide the actual drag and drop “drawing” of the HTML page that is not available on other platforms, however it is just a question of resources and time for us to plug our framework into comparable abilities of each platform. No ETA yet for it.