A friend of mine is fooling around and has the game screen stretched, but he also fixed it so that I can't pick any 32x32 or 16x16 mode. I know he's just experimenting with it and all, but is there any way to change the stretching to pixelated instead of this bicubic look? The icons are 8-bit and a stretched screen makes them look like total crap. :(

^ Yuck.
you can turn off opengl or find out the name of the default map panel and type in .winset"" where size = size in pixels, turning off opengl gives it the old look, you might notice some games (8 bit fan games) look kinda weird with 4.0
Where do I type in the .winset blahblah part? I tried copying it into the chat bar as if I were doing .configure or .ping but that didn't work.
You could always edit that persons interface file. And prevent him/her from disabling the resize. It probably didn't work because you need the name of the map.
I turned off OpenGL and that fixed the bicubic look, but I didn't notice that would knock out the transparency. Damned if I do, damned if I don't, it seems.

My problem is that I don't know what you're talking about when you mention default map panels. Do you mean the Edit Skin selection in "Options and Settings"?
I'm lost again. All I see is skin.dme and skin.dmf, but doubleclicking on either just takes me to a blank skin editor thing, as though I wanted to create a new one from scratch.

Edit: You're not trying to walk me through this on the assumption that I actually have the source, are you? I just want to change it on my end.
Okay, I think I found the map panel thing but I don't see any area where I can type in .winset"". :/