This isn't really an editor question, it's more in general and for icons and stuff: What program would you use to make an icon that has no background, like not even white or anything, so that when you use it as an icon like on your desktop, it doesn't have a background around it? I've tried using stuff like Gimpshop and others but when I save it and open it in Preview it always has a white background.
You should get Photoshop and save it as a transparent PNG, then copy and paste it as icon.
That always worked for me.
Yes, gimp or photoshop will do it. Just make sure you can see through to the checkerboard-background.

If you want a great Icon changer type that works great in step with Photoshop and other apps like that. Try Iconographer X, it's free now I believe, and it's really great. Link below:
http://www.mscape.com/
OS X comes with an icon converter in the tools. You could try out that. You'd probably have to install the dev tools if yiou haven't already.
Well, I got an image with no background and opened it in preview and it was fine, but when I did copy/paste into the picture of the game in Get Info, it appeared on my desktop with a black background. Should I be pasting it somewhere else, or is there a specific file type that I have to use? Thanks (if it helps, I used Gimp to make the picture)
What size is the icon you made?
adobemedia Wrote:What size is the icon you made?
It's 170 x 170.
What you have to do is convert it to a .icns file. Then, go to dim3 engine, right (or control) click-show package contents open the contents folder, the resources folder and replace the "dim3 Engine.icns".
For files/folders, I think copying the icns will keep the transparency, not sure though.