Please note that the following is not a supported configuration. At this time, Desktop Viewer is only officially supported and tested with XenDesktop. However, if you would like to use Desktop Viewer in your XenApp environments, please continue reading.
The information below is based upon the use of the 12.1 online plug-in and XenApp 6.0.
Enabling Desktop Viewer for XenApp
1. Logon to the machine hosting your Web Interface as an Admin user
2. Navigate to C:\Inetpub\wwwroot\Citrix\XenApp\conf for WI connections
3. Navigate to C:\Inetpub\wwwroot\Citrix\PNAgent\conf for PN Agent connections
4. Edit the WebInterface.conf file in both locations
5. Alter the configuration file so that ShowDesktopViewer=On

Desktop Viewer Overview
- Officially supported in XenDesktop environments
- It is included with the online plug-in and is installed by default on client devices
- Available in Windowed Mode or Full Screen Mode
- Integrates easily into single and multiple monitor environments
- Toolbar provides easy access to Display and HDX preferences
- Provides toolbar shortcuts to switch between multiple Hosted Shared Desktop sessions with ease

Desktop Viewer for XenApp Demonstration
For those of you, who are not familiar with Desktop Viewer, please view the following demonstration video for a basic overview of the available functionality. 

Current Limitations / Known Issues
- In order to use TWAIN or USB PnP devices within the Hosted Shared Desktop, the user must change the associated security preferences in Connection Center to Full Access
- WFICA32 may stop working in situations where network connectivity between the client and host is lost