Auto Redraw
Auto Redraw is used to automatically redraw the image each time the window contents or view is changed. Auto Redraw is on by default, and this is indicated by a check mark beside the command. Click View | Redraw | Auto Redraw or the 
button to toggle the command on and off. If Auto Redraw is disabled use Redraw or press the F5 key on the keyboard to redraw the image.