Looks great, and feels nice. One thing I would suggest is, with pen tool, add a feature that draws a line (from the previous pixel) if you push Shift down while moving the pixel around on the canvas, and outputs the line itself on mousedown (like in Gimp).
You can hold shift and click-and-drag to make straight lines, it's a bit different but the same end result. I see how that's handy for making sun feather shaped things though.
Looks like an advanced version of Pixothello :D
Will this have an animation-preview feature as well?
Yes, animation is planned at some point, it will work a bit different from Pixothello though.
hm, using it now to make some tiles, but how do I save or export them :D
I can only save and export as .pyxel. :<
Also, ctrl-a (select all) no ctrl - c?
File > Export tileset should do the trick. Or if you want to get the individual tile png's, you can get hacky and unzip the .pyxel file to rip out it's innards.
Selections are not implemented yet, but I'm working on it.
I am not a very good artist, but I love how well this program has allowed me to make quick, reasonably good looking "placeholder" tiles for a small project I am working on. I will definitely buy a real license when it is available. Congrats on the great work man