I'm not sure why i like reinventing the wheel since there's probably hundreds of tutorials about how to hide Firefox's context menu items, but reinvent i did. One of the cooler things i haven't seen much of in the existing tutorials is how to get a list of all the CSS selectors for all of Firefox's context menus (all 476) by searching the source code. I also cover how to grab them the ol' fashioned way, with Firefox's Developer Tools. Have a read.