What does emptyparts for an element in the skin ini file do?

I know it does something but can't quite figure out what.

It's probably obvious when you know.

Regards,
Paul

this is the list of the parts (states) in the "ImageFile" to ignore. TLB doesn't paint image from "ImageFile" for emptyParts. Usually you have to set this parameter into 0 because in the normal state of the button or the menu items are transparent.

Settings the emptyParts just improves the performance a bit.

Thanks Yuri, that answers another question I had which was why the first image (the normal state) in the image file is not painted.