The Navigator palette always displays a thumbnail view of the entire display window contents, regardless of which portion of the image is currently visible in the display window. A red rectangle indicates the area of the image that is currently visible in the display window.
Moving the Navigator rectangle adjusts your view of the display window accordingly.
To zoom out using the Navigator palette, position the rectangle over the area, and then drag the slider down.
If the entire image is visible in the display window, the rectangle appears around the entire display area of the Navigator palette.