Go to add ons and search for "lazarus form recovery", or in any case just search "form save" (for some strange reason I wasn't getting results with the former).

After that every post you make will be saved and you can recover it in a submenu pressing the right mouse button over the text field where you were writing it. For instance if you were replying to a thread and your computer crashed or something, you go back to that exact thread, press reply and then look for the submenu, all your posts will be saved there.

This is essential for someone like me who likes to write stuff on the net, I am tired of wasting minutes of my life and precious mental energy for some stupid browser crash or pressing the wrong key ruining it all.