I used to be able to do that with F9 (from NEI ?) but now I can't anymore. I uninstalled some mods like Steve's Factory Manager, Steve's Carts, Floodlights, etc) because I was not using them and didn't intend on using them either (I did it for lag reduction and decreased load time). It goes from red lines to red lines with green grids, before it cycled through more stuff, like blue walls, and the sky was yellow above forced chunks. Was that from the mods I've uninstalled ? Do I need to press something else to work ?