In current version of SkinEditor it is really convenient that when you close the invoked external picture editor the small window pops up letting for image replacement.
However, if you do not close the picture editor, just save the modified picture, you need to do that manually by entering reference to the same picture. It would be nice to get the possibility (F5?) to check for changed pictures. That would be specially useful if one uses external editor supporting layers and does not want to close it every time while adjusting details.