Library /sys$common/syshlp/net$mgmt_help.hlb about, Mouse usage  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The mouse is used to Select an entity; perform the Zoom, Expand and
    Collapse actions; and move around in the displays.

    Note:  Right-handed button arrangement is the default for the Session
    Manager.  If you are using the left-handed button arrangement instead,
    the action of mouse buttons described here is reversed.

  Additional Information (explode) :

• MB1
• MB3