Every other app I use on Mac OS X with any sort of tabs (iTerm, Safari, Chrome, Sublime Text, MacVim, Finder, etc. etc.) provides two menu options to move between them: 'Select Next Tab' and 'Select Previous Tab'. With these menu options, I can set a global keyboard shortcut in OS X that applies to *all* applications, so that moving between tabs is consistent across my apps. This works everywhere but Firefox, which doesn't have these menu options; instead I have to install a separate extension and set them manually. (The first such extension I tried works for some shortcut keys but for some reason not the ones I wanted; hoping another one will work.) Why doesn't Firefox provide these standard menu options?