I use Corel (formerly Jasc) Paint Shop Pro, but you can use any graphics editor you want. Many themers just use Gimp (I can't stand gimp though as it's not driven by standards and can be confusing if you have any experience with a professional graphics editing program). Be very careful with .9.png's they MUST have a 1px border with markers in pitch black #000000 marking the stretchable areas (left and top border) and the content areas (right and bottom border). If your border has a color other than transparent or pure black you will get many errors while compiling. If this happens, fix the first graphic that's listed and recompile to get the next error ;-) If your opening any png's from decompiled apk's, then you will run into an issue where they have been optimized for the platform, and most graphic editors make them look blotchy. If this is an issue for you, I have a tool on xda-developers that I designed to fix that problem... You can check out the thread here: http://forum.xda-developers.com/showthread.php?t=2216403 Good Luck ;-)