gtk: add missing type annotations ported from Vala bindings

https://bugzilla.gnome.org/show_bug.cgi?id=730745

gtk/gtkdialog.c

@@ -1942,7 +1942,7 @@ gtk_dialog_get_header_bar (GtkDialog *dialog)
  *
  * Returns the content area of @dialog.
  *
- * Returns: (transfer none): the content area #GtkBox.
+ * Returns: (type Gtk.Box) (transfer none): the content area #GtkBox.
  *
  * Since: 2.14
  **/

gtk/gtkfilechooserbutton.c

@@ -2954,7 +2954,7 @@ gtk_file_chooser_button_new (const gchar          *title,
 
 /**
  * gtk_file_chooser_button_new_with_dialog:
- * @dialog: the widget to use as dialog
+ * @dialog: (type Gtk.Dialog): the widget to use as dialog
  *
  * Creates a #GtkFileChooserButton widget which uses @dialog as its
  * file-picking window.

gtk/gtkinfobar.c

@@ -746,7 +746,8 @@ gtk_info_bar_get_content_area (GtkInfoBar *info_bar)
  * action area. The button widget is returned, but usually you don't
  * need it.
  *
- * Returns: (transfer none): the #GtkButton widget that was added
+ * Returns: (transfer none) (type Gtk.Button): the #GtkButton widget
+ * that was added
  *
  * Since: 2.18
  */

gtk/gtkmenushell.c

@@ -500,7 +500,7 @@ gtk_menu_shell_dispose (GObject *object)
 /**
  * gtk_menu_shell_append:
  * @menu_shell: a #GtkMenuShell
- * @child: The #GtkMenuItem to add
+ * @child: (type Gtk.MenuItem): The #GtkMenuItem to add
  *
  * Adds a new #GtkMenuItem to the end of the menu shell's
  * item list.

gtk/gtkoverlay.c

@@ -559,7 +559,8 @@ gtk_overlay_class_init (GtkOverlayClass *klass)
    * GtkOverlay::get-child-position:
    * @overlay: the #GtkOverlay
    * @widget: the child widget to position
-   * @allocation: (out caller-allocates): return location for the allocation
+   * @allocation: (type Gdk.Rectangle) (out caller-allocates): return
+   *   location for the allocation
    *
    * The ::get-child-position signal is emitted to determine
    * the position and size of any overlay child widgets. A

gtk/gtkplacessidebar.c

@@ -4084,7 +4084,7 @@ gtk_places_sidebar_class_init (GtkPlacesSidebarClass *class)
   /**
    * GtkPlacesSidebar::open-location:
    * @sidebar: the object which received the signal.
-   * @location: #GFile to which the caller should switch.
+   * @location: (type Gio.File): #GFile to which the caller should switch.
    * @open_flags: a single value from #GtkPlacesOpenFlags specifying how the @location should be opened.
    *
    * The places sidebar emits this signal when the user selects a location
@@ -4108,9 +4108,9 @@ gtk_places_sidebar_class_init (GtkPlacesSidebarClass *class)
   /**
    * GtkPlacesSidebar::populate-popup:
    * @sidebar: the object which received the signal.
-   * @menu: a #GtkMenu.
-   * @selected_item: #GFile with the item to which the menu should refer, or #NULL in the case of a @selected_volume.
-   * @selected_volume: #GVolume if the selected item is a volume, or #NULL if it is a file.
+   * @menu: (type Gtk.Menu): a #GtkMenu.
+   * @selected_item: (type Gio.File) (nullable): #GFile with the item to which the menu should refer, or #NULL in the case of a @selected_volume.
+   * @selected_volume: (type Gio.Volume) (nullable): #GVolume if the selected item is a volume, or #NULL if it is a file.
    *
    * The places sidebar emits this signal when the user invokes a contextual
    * menu on one of its items.  In the signal handler, the application may
@@ -4213,9 +4213,10 @@ gtk_places_sidebar_class_init (GtkPlacesSidebarClass *class)
   /**
    * GtkPlacesSidebar::drag-action-requested:
    * @sidebar: the object which received the signal.
-   * @context: #GdkDragContext with information about the drag operation
-   * @dest_file: #GFile with the tentative location that is being hovered for a drop
-   * @source_file_list: (element-type GFile) (transfer none): List of #GFile that are being dragged
+   * @context: (type Gdk.DragContext): #GdkDragContext with information about the drag operation
+   * @dest_file: (type Gio.File): #GFile with the tentative location that is being hovered for a drop
+   * @source_file_list: (type GLib.List) (element-type GFile) (transfer none):
+	 *   List of #GFile that are being dragged
    *
    * When the user starts a drag-and-drop operation and the sidebar needs
    * to ask the application for which drag action to perform, then the
@@ -4271,8 +4272,9 @@ gtk_places_sidebar_class_init (GtkPlacesSidebarClass *class)
   /**
    * GtkPlacesSidebar::drag-perform-drop:
    * @sidebar: the object which received the signal.
-   * @dest_file: Destination #GFile.
-   * @source_file_list: (element-type GFile) (transfer none): #GList of #GFile that got dropped.
+   * @dest_file: (type Gio.File): Destination #GFile.
+   * @source_file_list: (type GLib.List) (element-type GFile) (transfer none):
+   *   #GList of #GFile that got dropped.
    * @action: Drop action to perform.
    *
    * The places sidebar emits this signal when the user completes a

gtk/gtksettings.c

@@ -925,7 +925,7 @@ gtk_settings_class_init (GtkSettingsClass *class)
   g_assert (result == PROP_ERROR_BELL);
 
   /**
-   * GtkSettings:color-hash:
+   * GtkSettings:color-hash: (element-type utf8 Gdk.Color):
    *
    * Holds a hash table representation of the #GtkSettings:gtk-color-scheme
    * setting, mapping color names to #GdkColors.

gtk/gtkstatusbar.c

@@ -517,7 +517,7 @@ gtk_statusbar_remove_all (GtkStatusbar *statusbar,
  *
  * Retrieves the box containing the label widget.
  *
- * Returns: (transfer none): a #GtkBox
+ * Returns: (type Gtk.Box) (transfer none): a #GtkBox
  *
  * Since: 2.20
  */

gtk/gtkwidget.c

@@ -1801,7 +1801,8 @@ G_GNUC_END_IGNORE_DEPRECATIONS
   /**
    * GtkWidget::size-allocate:
    * @widget: the object which received the signal.
-   * @allocation: the region which has been allocated to the widget.
+   * @allocation: (type Gtk.Allocation): the region which has been
+   *   allocated to the widget.
    */
   widget_signals[SIZE_ALLOCATE] =
     g_signal_new (I_("size-allocate"),