nsIWindowCreator in Firefox 3.0

 Create a new window. Gecko will/may call this method, if made
      available to it, to create new windows.
      @param parent parent window, if any. null if not. the newly created
                    window should be made a child/dependent window of
                    the parent, if any (and if the concept applies
                    to the underlying OS).
      @param chromeFlags chrome features from nsIWebBrowserChrome
      @return the new window