Downgrade some Since tags

gdk/x11/gdkdisplay-x11.c

@@ -2652,6 +2652,8 @@ extern GdkNativeWindow      _gdk_x11_display_get_drag_protocol      (GdkDisplay
  *
  * See the X Session Management Library documentation for more information on
  * session management and the Inter-Client Communication Conventions Manual
+ *
+ * Since: 2.24
  */
 void
 gdk_x11_set_sm_client_id (const gchar *sm_client_id)

gdk/x11/gdkselection-x11.c

@@ -352,7 +352,7 @@ _gdk_x11_display_send_selection_notify (GdkDisplay       *display,
  * Returns: the number of strings stored in list, or 0,
  *     if the conversion failed
  *
- * Since: 3.0
+ * Since: 2.24
  */
 gint
 gdk_x11_display_text_property_to_text_list (GdkDisplay   *display,
@@ -400,6 +400,8 @@ gdk_x11_display_text_property_to_text_list (GdkDisplay   *display,
  *
  * Frees the array of strings created by
  * gdk_x11_display_text_property_to_text_list().
+ *
+ * Since: 2.24
  */
 void
 gdk_x11_free_text_list (gchar **list)
@@ -585,7 +587,7 @@ _gdk_x11_display_text_property_to_utf8_list (GdkDisplay    *display,
  *
  * Returns: 0 upon success, non-zero upon failure
  *
- * Since: 3.0
+ * Since: 2.24
  */
 gint
 gdk_x11_display_string_to_compound_text (GdkDisplay  *display,
@@ -705,7 +707,7 @@ _gdk_x11_display_utf8_to_string_target (GdkDisplay  *display,
  * Return value: %TRUE if the conversion succeeded,
  *     otherwise %FALSE
  *
- * Since: 3.0
+ * Since: 2.24
  */
 gboolean
 gdk_x11_display_utf8_to_compound_text (GdkDisplay  *display,
@@ -777,7 +779,7 @@ gdk_x11_display_utf8_to_compound_text (GdkDisplay  *display,
  *
  * Frees the data returned from gdk_x11_display_string_to_compound_text().
  *
- * Since: 3.0
+ * Since: 2.24
  */
 void
 gdk_x11_free_compound_text (guchar *ctext)

gdk/x11/gdkwindow-x11.c

@@ -865,7 +865,7 @@ x_event_mask_to_gdk_event_mask (long mask)
  *   window, or %NULL if the window has been destroyed. The wrapper
  *   will be newly created, if one doesn't exist already.
  *
- * Since: 3.0
+ * Since: 2.24
  */
 GdkWindow *
 gdk_x11_window_foreign_new_for_display (GdkDisplay *display,

gdk/x11/gdkxid.c

@@ -89,7 +89,7 @@ _gdk_x11_display_remove_window (GdkDisplay *display,
  * Return value: (transfer none): the #GdkWindow wrapper for the native
  *    window, or %NULL if there is none.
  *
- * Since: 3.0
+ * Since: 2.24
  */
 GdkWindow *
 gdk_x11_window_lookup_for_display (GdkDisplay *display,