The pen side switch can be set to two different customizable functions. You can use the switch whenever the pen tip is within 10 mm (0.4 inch) of the tablet active area. You do not have to touch the pen tip to the tablet in order to use the switch. See Using the pen.
The default side switch positions are:
Tip: To position a document or image within the active window, set a switch function to Pan/Scroll. Then press the pen button and move the pen tip across the tablet surface to reposition the image. Release the pen button or lift the pen tip from the surface when you are done.
In some application windows, the document will precisely follow the cursor as you move the pen tip. In others it will simply move in the same general direction as the screen cursor.