Perhaps you already had tried to add content to the new SDN Wiki using Firefox. Perhaps you got the same problem as I had with the Firefox Pop-up blocker. It limits the use of the Rich Text Editor. You have to add wiki.sdn.sap.com manually into the Exceptions. That is done via the Menu: Tools -> Options -> Content -> Block pop-up windows -> Exceptions.
Thanks to Eddy De Clercq who has taken this screenshot an an English Firefox Version.