Add documentation for gtk_window_set_titlebar

docs/reference/gtk/gtk3-sections.txt

@@ -5513,6 +5513,7 @@ gtk_window_get_resize_grip_area
 gtk_window_get_application
 gtk_window_set_application
 gtk_window_set_has_user_ref_count
+gtk_window_set_titlebar
 
 <SUBSECTION Standard>
 GTK_WINDOW

gtk/gtk.symbols

@@ -4051,6 +4051,7 @@ gtk_window_set_skip_pager_hint
 gtk_window_set_skip_taskbar_hint
 gtk_window_set_startup_id
 gtk_window_set_title
+gtk_window_set_titlebar
 gtk_window_set_transient_for
 gtk_window_set_attached_to
 gtk_window_set_type_hint

gtk/gtkwindow.c

@@ -3415,6 +3415,21 @@ gtk_window_set_geometry_hints (GtkWindow       *window,
   gtk_widget_queue_resize_no_redraw (GTK_WIDGET (window));
 }
 
+/**
+ * gtk_window_set_titlebar:
+ * @window: a #GtkWindow
+ * @titlebar: the widget to use as titlebar
+ *
+ * Sets a custom titlebar for @window.
+ *
+ * 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
+ * that is already visible, so you set the titlebar before calling
+ * gtk_widget_show().
+ *
+ * Since: 3.10
+ */
 void
 gtk_window_set_titlebar (GtkWindow *window,
                          GtkWidget *titlebar)

gtk/gtkwindow.h

@@ -348,6 +348,7 @@ gboolean gtk_window_resize_grip_is_visible (GtkWindow    *window);
 gboolean gtk_window_get_resize_grip_area   (GtkWindow    *window,
                                             GdkRectangle *rect);
 
+GDK_AVAILABLE_IN_3_10
 void     gtk_window_set_titlebar           (GtkWindow    *window,
                                             GtkWidget    *titlebar);