Images: native PNG .256 thumbs?

I wonder if it would be possible to create PNG .256 thumbs when the source image is a PNG file - to natively support transparency?

From tricking the Mac app into believing a file is a .jpg (just changed the extension, no type check here obviously) I didn’t notice adverse effects when using a .PNG thumb. It displayed fine - including transparency*. OK, the thumb’s size is bigger by ca. 20 KB. Would this be of concern - especially when PNG thumbs were limited to PNG source files?

*Well, I couldn’t actually see that but then that’s what I wanted. :wink: