The black Desktop Viewer toolbar does not show up in the user XenApp or XenDesktop ICA session.
The issue is caused by NOT having the ShowDesktopViewer parameter set to On in the WebInterface.conf file on the Web Interface server.
To resolve this issue, complete the following procedure:
- Logon to the machine hosting the Web Interface as an administrator user.
- Open the C:InetpubwwwrootCitrixXenAppconf folder for Web Interface connections.
- Open the C:InetpubwwwrootCitrixPNAgentconf folder for PNAgent connections.
- Edit the WebInterface.conf file in both these locations.
- Update the configuration file to remove the ‘#’ and set ShowDesktopViewer=On.
- It is officially supported in XenDesktop environments.
- It is included with the online plug-in and is installed by default on client devices.
- It is available in Windowed Mode or Full Screen Mode.
- It integrates easily into single and multiple monitor environments.
- The toolbar provides easy access to Display and HDX preferences.
- It provides toolbar shortcuts to switch between multiple Hosted Shared Desktop sessions with ease.
Read the original article here at the Citrix knowledgebase.