I prefer to use PNG instead of PMP to save my work. This is because you always get a preview with PNG file, but not with PMP.
However it always comes with a .PAL file which is a bit annoying as when you move files you always have to move both, otherwise the palette structure is lost.
I’d like to suggest an option to embedded the .PAL file into the PNG as a custom chunk, so that for users that want so, the PAL file is not written but hold inside the same PNG.
(or a PMP preview in explorer, which surely is a lot harder than the custom chunk )
So the images use alpha transpareny. The question is: will you want too keep it then you should continue using 32bit PNG
If you don’t need it, e.g. because the image effectively only uses simple transparency and not different alpha levels then just click here:
This will disable alpha transparency and enabled color index based transparency.
Also have a look here: