Use default file format for sprite sheets #1683
Hi @goobliata, I'll add another default extension for sprite sheets (and maybe for File > Export too). The issue here is that (I guess) most people will like to default to .ase (or .aseprite) in File > Save, and to .png in File > Export Sprite Sheet.
About File > Export, at the moment it uses png when we're trying to export a static file, or .gif when we try to export an animation. I guess this should be configurable too.