Immersive mode locks your mouse, keyboard, or both to only send messages to the host computer.
Keyboard Immersive Mode
Allows you to pass important Windows keys from the client to the host. These include things like Alt + Tab. If you have immersive mode off, that combination will be sent to the client computer. If immersive mode is on, that combination will be sent to the hosting computer.
Mouse Immersive Mode
Mouse immersive mode locks your mouse into the Parsec host. You cannot leave the Parsec window with your mouse if you have mouse immersive mode on. If the mouse's immersive mode is off, your mouse will not be locked into Parsec. As soon as you click outside the Parsec window on the client computer, all keys and mouse presses will be on the client computer. If you click back into the Parsec client window and your keyboard is in immersive mode, your Windows keys, like ctrl + alt + delete will pass to the hosting computer again.
Keep in mind that if you have multiple Parsec windows, it won't be possible to leave the active display with 'Mouse' immersive mode. For a setup where you have multiple displays, with each Parsec window set to fullscreen on both displays, it is recommended to use only the 'Keyboard' immersive mode.
Leaving immersive mode
It's possible to toggle immersive mode at any time with Ctrl+Shift+I (Cmd+Alt+I on macOS). It is also possible to temporarily detach all inputs from the stream by pressing Ctrl+Alt+Z (Cmd+Alt+Z on macOS). Detaching the input prevents any mouse and keyboard input from reaching the host, and prevents Parsec from 'eating' the keyboard inputs or locking your mouse cursor, until you click again onto the Parsec window.
Behavior in different operating systems
On macOS, HID Mode is required for Immersive Mode
If you are unable to enable Immersive Mode, ensure that HID Mode is set to "On." Enabling HID Mode requires Parsec to be restarted.
Android behavior
Although the option is available for Android, it does not work well at this time.