gtk:notebook-menu-label-text (notebook child)

notebook -- a gtk:notebook widget
child -- a gtk:widget child of a page of the notebook
text -- a string with the label text

The gtk:notebook-menu-label-text function retrieves the text of the menu label for the page containing child. The (setf gtk:notebook-menu-label-text) function creates a new label and sets it as the menu label of the child page.