Orig_sizex/orig_sizey isn't really documented in the wiki, so I thought I'd ask about it here.
Am I assuming correctly it's used for highres tiles to change dimensions of the 8-bit tile that is supposed to be replaced? For example, if the statusbar has 320x34 in 8bpp but you want to use a widescreen tile as a highres replacement, you would use something like orig_sizex 428 and orig_sizey 34.
What I was wondering: Sometimes when you turn off highres textures via menu, the original tiles won't show, just some black space. Is that because the 8bpp tile doesn't have the dimensions defined for the highres one or what?
