As someone somewhat active editor in SE, I have the need to edit several post per day. Some of them would be easier if I have the "Replace"/"Typeover" (the action when you press Insert) in Firefox. I've not able to activate this function nor I have figured out if I need an option before hand. So, how do I replace/typeover text in any text area in Firefox?
I'm not going to find and replace stings, but typeover while writing as I can do with a text editor.