[khininger]

like you said, "You create a folder with the desired category images and then upload that via FTP to your Images directory. Then in the Forum Manager you type in the prefix for that folder and your finished." - except you dont load all the images from all themes into the same directory, you create a subdirectory and load your images there and type in that location in styles manager.

for example, let's say you have a theme with helmets and a theme with teddy bears. so instead of loading both helmets and bears into forum/images, you create two subfolders there: forum/images/helmets and forum/images/bears, load the images accordingly, and type these locations in styles manager.