notebook at the given position, specifying
the widget to use as the label in the popup menu.gtkNotebookInsertPageMenu(object, child, tab.label = NULL, menu.label = NULL, position = -1)objectchildGtkWidget to use as the contents of the page.tab.labelGtkWidget to be used as the label for the page,
or NULL to use the default label, 'page N'. [ allow-none ]menu.labelNULL, and tab.label
is a GtkLabel or NULL, then the menu label will be
a newly created label with the same text as tab.label;
If tab.label is not a GtkLabel, menu.label must be
specified if the page-switch menu is to be used. [ allow-none ]position