If smart panning is enabled, as you move selected items in a viewport, the viewport will automatically pan to always show the items. It remembers the original position and contents of the viewport before panning and will try and restore that view if at all possible.
You can always pan by using one of the direction arrows. You can also pan by holding down the middle mouse button and dragging the mouse. This will work when you're doing most things. Additionally, if you rotate the middle mouse wheel the view will zoom in/out. By rotating the middle mouse button and holding the middle mouse button down while dragging the mouse you can quickly change the view.
You can turn smart panning on/off by click the 
button in the status bar.