This is the typical thing passed here and what most users want, so we
should mention it here, rather than requiring users to figure it out.
*
* Sets a custom titlebar for @window.
*
+ * A typical widget used here is #GtkHeaderBar, as it provides various features
+ * expected of a titlebar while allowing the addition of child widgets to it.
+ *
* If you set a custom titlebar, GTK+ will do its best to convince
* the window manager not to put its own titlebar on the window.
* Depending on the system, this function may not work for a window