Tracking the mouse off-window

I managed to come up with a workaround until the people at Unity Technologies let us get the mouse position. A MouseBlocker GameObject with a few simple components:

• An Image with no sprite, and a transparent tint (aka alpha = 0)

• A CanvasGroup

• A MonoBehaviour that goes like:

   public Camera referenceCamera;
   private CanvasGroup group;
   public Vector2 lastMousePos;
   public Vector2 mouseDelta;
     
   public static bool BlockMouseInput = false;
     
   void Update() {
       Vector2 currMousePos = Input.mousePosition;
   
       Vector3 newpos;
       RectTransformUtility.ScreenPointToWorldPointInRectangle(((RectTransform)this.transform), currMousePos, referenceCamera, out newpos);
       transform.position = newpos;
     
       mouseDelta += new Vector2(Input.GetAxisRaw("Mouse X"), Input.GetAxisRaw("Mouse Y"));
       if((Vector3)lastMousePos != Input.mousePosition) {
           mouseDelta = Vector2.zero;
     
           lastMousePos = Input.mousePosition;
       }
     
       if(group == null) group = GetComponent<CanvasGroup>();
       group.blocksRaycasts = BlockMouseInput = (mouseDelta.sqrMagnitude > 0.15f);
   }
  
  
  

It takes care if pretty much everything under the uGUI with the CanvasGroup blocking the Raycasting, but anything referencing Input.GetAxis on any of the mouse axes should check BlockMouseInput first.