It took me awhile to find the correct instructions for allowing pasting of rich text in Firefox. I was trying to enable the pasting of rich text into htmlarea/fckeditor box and I kept getting a security popup from Firefox. The page it referred me to a mozilla page and those instructions did not work for Firefox. After I searched for "user.js firefox"
, I found a page that said Firefox looks for the user.js file in a different directory than Mozilla. When I placed the modified user.js in the correct directory, I could paste rich text.