The Citrix NetScaler Gateway is quite commonly used as a frontend to XenDesktop and provides the necessary security controls. Thus, applying policies for the NetScaler Gateway is a logical point of enforcement for XenDesktop sessions. You can create policies that apply to the NetScaler Gateway connections.
To do this, you would create Citrix policies that can be applied to different access scenarios. You can base them on elements such as authentication strength, logon location, and user device, including endpoint analysis for the software updates and antivirus. This is also an excellent point to apply client-side drive mapping controls, cutting and pasting controls, and local printing controls.