gtk:application-window-help-overlay (window)

window -- a gtk:application-window widget
overlay -- a gtk:shortcuts-window widget

The gtk:application-window-help-overlay function gets the shortcuts window associated with the application window. The (setf gtk:applicaton-window-help-overlay) function associates a shortcuts window with the application window, and sets up an action with the name "win.show-help-overlay" to present it.