Setting this property to true indicates the view controller’s preference
to lock the pointer, although the system may not honor the request.
For the system to consider locking the pointer:
The scene must be full screen, not in Split View or Slide Over, with no
other apps in Slide Over.
The scene must be in the UISceneActivationStateForegroundActive state.
The ScummVM iOS7 client fulfills the above so the pointer is locked.
Locking the pointer hides the OS cursor (the dot), however that's wanted
since the ScummVM engine draws its own pointer.