Update (allow-none) annotations

The annotation has been deprecated in favor of (nullable) and/or
(optional).

src/core/display.c

@@ -2526,7 +2526,7 @@ mru_cmp (gconstpointer a,
  * @display: a #MetaDisplay
  * @type: type of tab list
  * @screen: a #MetaScreen
- * @workspace: (allow-none): origin workspace
+ * @workspace: (nullable): origin workspace
  *
  * Determine the list of windows that should be displayed for Alt-TAB
  * functionality.  The windows are returned in most recently used order.
@@ -2595,7 +2595,7 @@ meta_display_get_tab_list (MetaDisplay   *display,
  * @display: a #MetaDisplay
  * @type: type of tab list
  * @workspace: origin workspace
- * @window: (allow-none): starting window
+ * @window: (nullable): starting window
  * @backward: If %TRUE, look for the previous window.
  *
  * Determine the next window that should be displayed for Alt-TAB

src/core/keybindings.c

@@ -3187,7 +3187,7 @@ handle_switch_vt (MetaDisplay     *display,
 /**
  * meta_keybindings_set_custom_handler:
  * @name: The name of the keybinding to set
- * @handler: (allow-none): The new handler function
+ * @handler: (nullable): The new handler function
  * @user_data: User data to pass to the callback
  * @free_data: Will be called when this handler is overridden.
  *

src/core/prefs.c

@@ -180,7 +180,7 @@ typedef struct
 
 /**
  * MetaStringPreference:
- * @handler: (allow-none): A handler. Many of the string preferences
+ * @handler: (nullable): A handler. Many of the string preferences
  * aren't stored as strings and need parsing; others of them have
  * default values which can't be solved in the general case.  If you
  * include a function pointer here, it will be called instead of writing
@@ -192,7 +192,7 @@ typedef struct
  * in particular the @result (out) parameter as returned by
  * g_settings_get_mapped() will be ignored in all cases.
  * This may be %NULL.  If it is, see "target", below.
- * @target: (allow-none): Where to write the incoming string.
+ * @target: (nullable): Where to write the incoming string.
  * This must be %NULL if the handler is non-%NULL.
  * If the incoming string is %NULL, no change will be made.
  */

src/core/window.c

@@ -4789,7 +4789,7 @@ meta_window_get_icon_geometry (MetaWindow    *window,
 /**
  * meta_window_set_icon_geometry:
  * @window: a #MetaWindow
- * @rect: (allow-none): rectangle with the desired geometry or %NULL.
+ * @rect: (nullable): rectangle with the desired geometry or %NULL.
  *
  * Sets or unsets the location of the icon corresponding to the window. If
  * set, the location should correspond to a dock, task bar or other user
@@ -7280,7 +7280,7 @@ meta_window_get_frame_type (MetaWindow *window)
  *
  * Gets a region representing the outer bounds of the window's frame.
  *
- * Return value: (transfer none) (allow-none): a #cairo_region_t
+ * Return value: (transfer none) (nullable): a #cairo_region_t
  *  holding the outer bounds of the window, or %NULL if the window
  *  doesn't have a frame.
  */
@@ -7325,7 +7325,7 @@ meta_window_is_attached_dialog (MetaWindow *window)
  *  - there is no 3rd window stacked between both tiled windows that's
  *    partially visible in the common edge.
  *
- * Return value: (transfer none) (allow-none): the matching tiled window or
+ * Return value: (transfer none) (nullable): the matching tiled window or
  * %NULL if it doesn't exist.
  */
 MetaWindow *