instead of the action-area.
For technical reasons, this property is declared as an integer property, but you should only set it to true or false.
## Creating a dialog with headerbar
Builtin [gtk.dialog.Dialog] subclasses such as [gtk.color_chooser_dialog.ColorChooserDialog] set this property according to platform conventions (using the property@Gtk.Settings:gtk-dialogs-use-header setting).
Here is how you can achieve the same:
g_object_get (settings, "gtk-dialogs-use-header", &header, NULL);
dialog = g_object_new (GTK_TYPE_DIALOG, header, TRUE, NULL);