Add “Clear Field” Control+U to Firefox

On a Unix system, especially Linux, when you've got an input form, you often have the option to hit Control+U keys combination to clear it. It's really useful as you sometimes have something in the clipboard which you'd like to paste with middle click, but don't want to lose by selecting the all field.To add the Control+U option to Firefox, and by the way to all the GTK2 apps, you just need to add to the file "~/.gtkrc-2.0" (You may have to create it first) the following line :

gtk-key-theme-name = "Emacs"

With that, just restart Firefox, and now, when the cursor is in a filled input field just hit Control+U and it will be erased. Note that it won't disable the default behavior of Control+U elsewhere in Firefox, which open the source code of the current page.