Preview Window in second screen

Hi, I have a suggestion for Aseprite, can you ad support for multiscreen? Because I work with more than one screen and when I try to grab the preview window outside the main Aseprite window, it disappear.

[dacap]

Hi @pennaverde, it's already planned in #250, but it needs #139 first (which is a work-in-progress) to support multiple windows on the screen. It's something I'd love to have soon.