By default, XenDesktop users with Citrix Receiver 3.x can choose window size as they please. I recently had a customer who required (through use of thinclients with write-filter) that the desktop always launched in fullscreen.
Citrix have never been particularly good with documentation; so it’s no surprise that this key:
…is undocumented. But it works! Problem solved, and one less headache.
Thanks to Andrew Morgan at the Citrix forums.