That worked, although the instructions on the JDarkRoom page are a
tiny bit misleading. On my system (Ubuntu 9.04), there was no folder
called 'conf'; jdarkroom stored its properties in '~/.jdarkroom' by
default.
Someone should probably change the instructions to reflect this.
Oh, and it would be nice to have a checkbox in the program to disable
native look and feel. I think it should be the default.