Rated 5 out of 5 stars

Please, please, please add this How-To link to your description -- http://kb.mozillazine.org/Keyconfig_extension instead of saying the rest is self-explanatory. I had to install DOM Inspector to get the menu item to replace /*CODE*/

Also Control+Shift+F12 does not do anything for me on my Thinkpad T460s, Win10Pro, TB 60.4.0 32-bit Had to get there using Tools -- > Keyconfig ...