1.6.4 doesn't like glass to have only 1 side of it as glass, and the rest of it as caulk. Switches was some wierd thing with my shaders, that oddly enough happened when I tried 1.6.4 lol but it works now. Everything looks to be as it should, however I see no real difference over 1.5. Compile times are the same, that's for sure lol.