C-w is already a highly used shortcut system-wide on my machine, so I’d like to make a different shortcut for close-tab – say, F4. How can I make this change in Firefox? I felt the frustration of several Firefox questioners who asked the same thing and were answered as if they just didn’t know the shortcut, missing the point entirely. On Reddit, though, I receive two excellent answers. One is the easy solution, with a handy plugin that takes care of it.