title: Greasemonkey Add On does not work properly
body: <p>I've installed the Greasemonkey Add On but I can neither install any scripts nor I can create my own scripts. When I click on the Add On in the upper menu bar I see following entries: </p>
  
  <ul>
  <li>Greasemonkey is active</li>
  <li>New user script ...</li>
  <li>Greasemonkey home page</li>
  <li>Greasemonkey wiki</li>
  <li>Get User Scripts</li>
  </ul>
  
  <p>When I click on "New User Script ..." nothing happens, just sometimes it opens like 5 tabs of an empty script.</p>
  
  <p>I am using Firefox 57.0.2 (64 bit)
  and Windows or Ubuntu (latest versions) </p>
  
  <p>Same behavior on both Operating systems</p>
  
  <p>Any ideas how I can fix this?</p>