A: To enable multiple monitors edit the web.config file in the StoreWeb-directory on the StoreFront server. The default location is c:\inetpub\wwwroot\citrix\Storeweb\.
In the web.config file, change showDesktopViewer=true to showDesktopViewer=false and save the file.
Citrix Discussions - XenDesktop 7 published desktop multiple-monitor configuration