There are two methods to perform the expand/collapse action.  The
     easiest way is to double-click the left-most mouse button on an entity in
     the main window.  (Of course, if you have changed your Session Manager
     Options and are using the Left-Handed Mouse Button Arrangement, use the
     right-most button instead.)

     Another way to expand or collapse an entity is to single click the
     left mouse button on the entity to select it and then select Expand or
     Collapse from the Actions pulldown menu.