Ctz fixed the parallax shader in FH2, but it requires the client_shaders.zip in the mods/bf2 to be replaced when the mod is played. That's why FH2 needs to be run via a special program (fh2.exe) which takes care of swapping the file, to make sure BF2 continues to work.
If other mods want to fix the same bug, they can borrow our shader.