(gobject:define-gflags "GtkDialogFlags" dialog-flags
  (:export t
   :type-initializer "gtk_dialog_flags_get_type")
  (:modal               #.(ash 1 0))
  (:destroy-with-parent #.(ash 1 1))
  (:use-header-bar      #.(ash 1 2)))  

:modal

Make the constructed dialog modal.

:destroy-with-parent

Destroy the dialog when its parent is destroyed.

:use-header-bar

Create the dialog with actions in the header bar instead of an action area.