Selection of this option with the mouse permits windowing in (zoom in) on any square sub-area of the current window. The user is first prompted to indicate by means of the mouse the position of the lower left-hand corner of the new display area and then the upper right-hand corner. The outline of the new window is shown by rubber-banding as the upper right-hand corner follows the mouse around. After the mouse is clicked, the new window is automatically squared off and the display is refeshed to show the required area at higher magnification.