Re-installing the Connector Add-onEdit online
  
  Note: The Oxygen Content Fusion Connector add-on comes pre-installed in
        Oxygen XML Editor or Oxygen XML Author starting with version 21.0.
      The add-on is compatible with Oxygen XML Editor/Author version 19.0 or
      later.
    If you are using a version of 19.0 through 20.1, or the Oxygen Content Fusion
        Connector add-in was uninstalled, you can re-install it by following these steps:
    - In Oxygen XML Editor or Oxygen XML Author, go to Help / Install new add-ons to open an add-on selection dialog box.
- Enter or paste https://www.oxygenxml.com/InstData/Addons/default/updateSite.xml in the Show add-ons from field or select it from the drop-down menu.
- Select Oxygen Content Fusion Connector add-on and click Next.
- Select the I accept all terms of the end user license agreement option and click Finish.
- Restart the application.
Result: The  Show Content Fusion Task
        Manager button is now available on the toolbar. Clicking it will open the Content Fusion Task
          Manager view.
Show Content Fusion Task
        Manager button is now available on the toolbar. Clicking it will open the Content Fusion Task
          Manager view. 
