GComponentObservable    GComponentObservable adds the observable
                        interface
GEdit                   The GEdit class adds some methods beyond the
                        spec: 'set_error', 'clear_error',
                        'validate_value'
GMessage                subclass for message dialog
GTree                   Base class
GTreeBase               Base class
add_editable_cell_renderer
                        make a view column for the given type of
                        variable
ensure_type             S3 generic to ensure we don't change data type
                        when assigning into column
gWidgets2RGtk2-package
                        gWidgets2Rtk2
getWidget.RGtkObject    method for stopping getWidget
guiWidgetsToolkitRGtk2-class
                        toolkit class for RGtk2
isFirstMouseClick       Return TRUE if first mouse click
isRightMouseClick       Return TRUE/FALSE if right mouse click
