I just got a V3. I have the camera set to AF-C. If I click on the center of the focus selector switch, it shows a box with small arrows, and I can move that box anywhere in the viewfinder. Now, if I click it again, it turns yellow, and if I move the camera that box moves all over the screen on it's own. I haven't found information in the manual on this. Can anyone help me understand what this is doing?