Why do you do S-C-x in Firefox? Are you using some add-on that gives
you Emacs bindings there, or?
no you misunderstood me, I want to avoid to learn any new emacs
keybindings that have a very different meaning in other applications.
e.g C-w closes a tab in FF, thats why I want to restrict me to always use C-x for cutting, otherwise I have restore FF-Windows 10 times per day.