I take it you mean the button icons, not the main app icon.
That info should be in the help file in all the places a graphic file can be specified. I've just this minute, finally found the info in part of the help file that doesn't apply to what I am doing, to whit Image under the
obsolete method LoadPicture. No wonder I hadn't looked there!
Thanks for the info. I have a freebie called IcoFx which fortunately allows export to all your supported formats, which is lucky for me!
EDIT: Having done that, I can advise
not converting to bmp format, you lose any transparent bits. I settled on gif which worked fine.