This is used to scroll through the list of entries available for the mode you are currently exploring. Clicking on the arrows at the top and bottom of the bar will scroll the index one line at a time. Dragging the scroll bar slider will cause the index to jump proportionately to the point where you dragged. Clicking above the slider bar jumps the index back by one page (7 entries at a time). Clicking below the slider bar jumps the index forward by one page.
