A mod for Planescape: Tormentpst_fog.zip ( source )
If the game's video resolution is increased with the The Bigg's Widescreen Mod then the checkerboard like fog-of-war creates the illusion of shimmering/tearing.
This mod darkens the tiles covered by fog-of-war by 25% instead of color-keying. It also has more reliable vsync, without risking performance problems, by switching the final display step to use OpenGL.
This mod conflicts a little with Ghostdog's UI mod. So I started on that but I don't remember where I derailed.