This appendix documents all the standard classes, their methods, and
their attributes.  The parameters for each moethod can be found in the
appropriate include file.  Each attribute is followed by a code that
lists the methods that apply to that attribute.  The codes are as
follows:

    I       OM_NEW
    S       OM_SET
    G       OM_GET
    N       OM_NOTIFY
    U       OM_UPDATE

                            rootclass
                               /
                 _____________/____________
                /         /                \
               /         /                  \
           icclass      /                gadgetclass
             /         /                      \
            /         /         _______________\___________________
           /     imageclass    /           /         \             \
          /         /         /           /           \             \
     modelclass    /      propgclass  strgclass  buttongclass  groupgclass
                  /                                     \
                 /                                       \
         _______/___________________________        frbuttongclass
        /         \            \            \
       /           \            \            \
  frameiclass  sysiclass  fillrectclass  itexticlass