Hi Daniel,
first of all, compliments again for Pyxel Edit. All the people to which I'm showing it fall in love with it and after a few days start using it :)
I have one important feature suggestion which would be especially great for people like me, which use Pyxel Edit with Unity. An option, when exporting PNGs, to automatically crop the eventual transparency borders and export the image with a size that fits exactly the visible content. It would definitely be a life saver in order to achieve optimal texture atlas sizes. And that way, we could have a single pyxel file where we could create various drawings, without worrying that we'll have to crop the PNGs later.
Other than that, it would be awesome if each file remembered where you exported it last time, making the export procedure less tiring :)
Cheers!