Move your mouse near to one of the four sides of your computer screen, specifically in regions where there is no any navigational UI element. The "Overview Thumbnail" will come out.
 

Left-click to zoom-in, shift + left-click to zoom-out, and Click-drag to pan the image below. Click at one of the "Overview Thumbnails", and you will be "transported" to the place represented. Click or Drag at the bottom-left "Overview Navigator" to pan or zoom the actual panorama.

Scroll forward or backward to zoom-in or zoom-out respectively (in more exact amount). The "Overview Navigator" also detects scroll for zoom operations [Mouse picture by openclipart.org].

Hit or hold one or two of the W or S or A or D key to pan Up, Down, Left, Right, or diagonal respectively.
Hit or hold F or J key to zoom-out or zoom-in respectively.