I've grown accustomed to writing longer comments or posts in an external editor, simply because I've too frequently experienced browser crashes, or an inadverte

I've grown accustomed to writing longer comments or posts in an external editor, simply because I've too frequently experienced browser crashes, or an inadvertent (or absent-minded) screen refresh. Alt-backspace is my worst offender, as I use that ALL the time in the shell for text editing, whereas in a browser it navigates backwards. Worst of all, I can't seem to find a way to alter the keybinds, or (more importantly) the mouse-5-means-go-back gesture.