You can use the Hotkey combination to grab input focus and Hotkey combination to release input focus group policy settings to configure keyboard shortcuts for input focus.

You can use the Automatic input focus in a virtual desktop window group policy setting to send input to the remote desktop automatically when a user brings the remote desktop to the front. These features are useful for users who cannot use mouse clicks to grab and release a remote desktop. For more information, see Using Group Policy Settings to Configure Horizon Client