Mouse Controls 
    Several basic surface and volume viewing and
      navigation functions are controlled with the mouse and are only
      active when the mouse cursor is within the Viewing
            Area.  
    
      - Rotate: hold down the left
            mouse button and move the mouse back and forth and up
          and down. Note that the rotation function is not active in Volume
                View. All other mouse controls are active in
          all views.
      - Zoom: press the
            Command/Ctrl key + the left mouse button
          and move the mouse up and down. If you have a mouse wheel, you
          can also scroll up to zoom out or scroll down to zoom in.
      
      - Pan: (move the brain
          surface to a different part of the Viewing Area), press
            the shift key + the left mouse button
          and move the mouse left, right, up, or down. 
      - ID: To identify a brainordinate,
          click on the brain surface or volume slice. A sphere will
          appear where the surface was clicked. Also, the Information
                window will pop up, showing information on
          the particular vertex/voxel that was clicked. 
 
      
        - The color and size of the ID sphere can
            be adjusted using the Properties
            button in the Information window.  
 
      
        - Reclicking on the sphere deselects that
            brainordinate and the sphere will disappear.
      - Right clicking on a
              surface or volume slice, brings up a menu of
          options depending on what is loaded (see images). 
      - Right clicking in the Viewing Area,
          but not on a surface or volume, pops up the single option to
          Remove All Vertex Identification Symbols.
 
    
    
    
    
    