Add to that using C-q often in Emacs to insert literal characters when using sth. like quail, and then forgetting you're in a text area and not in Emacs and hit

Add to that using C-q often in Emacs to insert literal characters when using sth. like quail, and then forgetting you're in a text area and not in Emacs and hitting C-q. Fortunately Firefox restores the content of the text area...