This button must be clicked to be activated. Once activated you can use it on the map in the following ways.

You can click on the map to move the map so it is centered on the point of your click.

You can also drag the map by holding down the mouse button as you move your mouse. Once the map is where you want it, release the mouse button the map should be drawn in the new location.

Click once on the button to zoom to the original extent when you first loaded the map.