The background is maintained independently of the images. Thus, if an image is moved over the background or another image, the background is not disturbed. When many images are simultaneously present, it is often convenient to keep most of them out of the way by stacking them up or moving them out of the visible region, off the edge of the screen. Alternatively, unused images can be changed into icons. If an image gets lost off the edge, it can be located by selecting ``Select image" or ``About the image''.
Images can be moved around by clicking on the small arrows in the information area. The distance by which a single click on the arrow moves the image is adjustable by pressing the gray ``+'' or ``-'' keys, or by selecting ``Cursor movement rate'' from the ``Configuration'' menu.
When the mouse cursor passes over an edge of an image, it changes from a diagonal arrow to double arrows. Clicking the left mouse button at this point, will ``grab'' the image. Continue pressing the mouse button, move to a new location, and then release. The image is then moved to the new location. The same is true for message boxes, graphs, dialog boxes, the colormap window, and information windows.
Edge-grabbing of images is prevented if the Left Alt, Caps Lock, or Shift keys are depressed. This makes it easier to select areas near the edge of the image.
If the Shift key is depressed, clicking the mouse sets a point on the image. Shift-clicking on a different point on the same image causes the area between the two points to be selected. Since shift-clicking is unaffected by the position of the image with respect to the screen, this feature makes it possible to select regions that are larger than the size of the screen.