With Parallels RAS 17, it's possible to create the custom button for Windows Clients. The Custom Menu pane allows you to add a menu item to the Help menu in a white-labeled Parallels Client for Windows. The button can be created in RAS Console > Farm > Theme > New or Existing Theme > Custom Menu. The menu button may contain the action of a process (e.g. notepad.exe), URL or any command line that can be deployed on the Windows platform.
For example, if you enter "&Notepad" in the Menu item field and "notepad.exe" in the Command field, a new menu item will appear under the Help menu in every white-labeled Parallels Client for Windows connecting to this farm. The item will be named Notepad (with the "N" being the shortcut) and it will open the Notepad.exe application when clicked. The Command field can contain an executable name, a URL, or any other command that can be properly executed on a Windows machine. For instance, you can add a menu item specifying a URL of your Helpdesk solution, so your users can easily reach it when needed.
After defining a Windows client theme, you can also create a client package for mass distribution. For more information, read KB 124489.