Reimplement the main toolbar's "prefer-item" feature.

This fixes a bug in the old implementation where the application could
crash after a second shell window was created and destroyed, because a
signal handler with the destroyed shell window as the closure was left
connected.

But moreover this simplifies the implementation by using a property
binding plus transform function instead of juggling signal handlers,
and also adds code comments where things get a little tricky.

Removed (now unused) functions:

  e_shell_window_get_toolbar_new_prefer_item
  e_shell_window_set_toolbar_new_prefer_item

3 files changed, 39 insertions, 118 deletions

diff --git a/shell/e-shell-backend.c b/shell/e-shell-backend.c
index 0261d8a3e2..d30e698981 100644
--- a/shell/e-shell-backend.c
+++ b/shell/e-shell-backend.c
@@ -252,11 +252,6 @@ shell_backend_dispose (GObject *object)
 		priv->shell_view_class = NULL;
 	}
 
-	if (priv->prefer_new_item) {
-		g_free (priv->prefer_new_item);
-		priv->prefer_new_item = NULL;
-	}
-
 	if (priv->notify_busy_handler_id > 0) {
 		g_signal_handler_disconnect (
 			object, priv->notify_busy_handler_id);
@@ -279,6 +274,7 @@ shell_backend_finalize (GObject *object)
 
 	g_free (priv->config_dir);
 	g_free (priv->data_dir);
+	g_free (priv->prefer_new_item);
 
 	/* Chain up to parent's finalize() method. */
 	G_OBJECT_CLASS (e_shell_backend_parent_class)->finalize (object);
diff --git a/shell/e-shell-window.c b/shell/e-shell-window.c
index 57c94df573..0bc5a51514 100644
--- a/shell/e-shell-window.c
+++ b/shell/e-shell-window.c
@@ -81,68 +81,40 @@ shell_window_menubar_update_new_menu (EShellWindow *shell_window)
 	gtk_widget_show (widget);
 }
 
-static void	shell_window_backend_prefer_item_changed_cb
-						(EShellBackend *backend,
-						 GParamSpec *pspec,
-						 EShellWindow *shell_window);
-
 static void
-shell_window_toolbar_update_new_menu (EShellWindow *shell_window,
+shell_window_toolbar_update_new_menu (GtkMenuToolButton *menu_tool_button,
                                       GParamSpec *pspec,
-                                      GtkMenuToolButton *menu_tool_button)
+                                      EShellWindow *shell_window)
 {
 	GtkWidget *menu;
 
 	/* Update the "New" menu tool button submenu. */
 	menu = e_shell_window_create_new_menu (shell_window);
 	gtk_menu_tool_button_set_menu (menu_tool_button, menu);
-
-	if (pspec && g_strcmp0 (pspec->name, "active-view") == 0) {
-		EShellView *shell_view;
-		EShellBackend *shell_backend;
-
-		shell_view = e_shell_window_peek_shell_view (
-			shell_window,
-			e_shell_window_get_active_view (shell_window));
-		g_return_if_fail (shell_view != NULL);
-
-		shell_backend = e_shell_view_get_shell_backend (shell_view);
-
-		g_signal_handlers_disconnect_by_func (
-			shell_backend,
-			shell_window_backend_prefer_item_changed_cb,
-			shell_window);
-
-		g_signal_connect (
-			shell_backend, "notify::prefer-new-item",
-			G_CALLBACK (shell_window_backend_prefer_item_changed_cb),
-			shell_window);
-
-		shell_window_backend_prefer_item_changed_cb (
-			shell_backend, NULL, shell_window);
-	}
 }
 
-static void
-shell_window_backend_prefer_item_changed_cb (EShellBackend *backend,
-                                             GParamSpec *pspec,
-                                             EShellWindow *shell_window)
+static gboolean
+shell_window_active_view_to_prefer_item (GBinding *binding,
+                                         const GValue *source_value,
+                                         GValue *target_value,
+                                         gpointer user_data)
 {
-	EShellView *shell_view;
+	GObject *source_object;
+	EShell *shell;
 	EShellBackend *shell_backend;
+	const gchar *active_view;
+	const gchar *prefer_item;
 
-	shell_view = e_shell_window_peek_shell_view (
-		shell_window,
-		e_shell_window_get_active_view (shell_window));
-	g_return_if_fail (shell_view != NULL);
+	active_view = g_value_get_string (source_value);
 
-	shell_backend = e_shell_view_get_shell_backend (shell_view);
-	if (shell_backend != backend)
-		return;
+	source_object = g_binding_get_source (binding);
+	shell = e_shell_window_get_shell (E_SHELL_WINDOW (source_object));
+	shell_backend = e_shell_get_backend_by_name (shell, active_view);
+	prefer_item = e_shell_backend_get_prefer_new_item (shell_backend);
 
-	e_shell_window_set_toolbar_new_prefer_item (
-		shell_window,
-		e_shell_backend_get_prefer_new_item (shell_backend));
+	g_value_set_string (target_value, prefer_item);
+
+	return TRUE;
 }
 
 static void
@@ -473,12 +445,26 @@ shell_window_construct_toolbar (EShellWindow *shell_window)
 	gtk_toolbar_insert (GTK_TOOLBAR (toolbar), item, 0);
 	gtk_widget_show (GTK_WIDGET (item));
 
-	g_signal_connect (
-		shell_window, "notify::active-view",
-		G_CALLBACK (shell_window_toolbar_update_new_menu),
-		GTK_MENU_TOOL_BUTTON (item));
+	/* XXX The ECalShellBackend has a hack where it forces the
+	 *     EMenuToolButton to update its button image by forcing
+	 *     a "notify::active-view" signal emission on the window.
+	 *     This will trigger the property binding, which will set
+	 *     EMenuToolButton's "prefer-item" property, which will
+	 *     invoke shell_window_toolbar_update_new_menu(), which
+	 *     will cause EMenuToolButton to update its button image.
+	 *
+	 *     It's a bit of a Rube Goldberg machine and should be
+	 *     reworked, but it's just serving one (now documented)
+	 *     corner case and works for now. */
+	g_object_bind_property_full (
+		shell_window, "active-view",
+		item, "prefer-item",
+		G_BINDING_SYNC_CREATE,
+		shell_window_active_view_to_prefer_item,
+		(GBindingTransformFunc) NULL,
+		NULL, (GDestroyNotify) NULL);
 
-	g_signal_connect_swapped (
+	g_signal_connect (
 		item, "notify::prefer-item",
 		G_CALLBACK (shell_window_toolbar_update_new_menu),
 		shell_window);
@@ -1520,62 +1506,6 @@ e_shell_window_set_toolbar_visible (EShellWindow *shell_window,
 }
 
 /**
- * e_shell_window_get_toolbar_new_prefer_item:
- * @shell_window: an #EShellWindow
- *
- * Returns: name of preferred item on the New button for current view.
- *
- * Since: 3.4
- **/
-const gchar *
-e_shell_window_get_toolbar_new_prefer_item (EShellWindow *shell_window)
-{
-	GtkWidget *toolbar;
-	GtkToolItem *item;
-
-	g_return_val_if_fail (shell_window != NULL, NULL);
-	g_return_val_if_fail (E_IS_SHELL_WINDOW (shell_window), NULL);
-
-	toolbar = e_shell_window_get_managed_widget (shell_window, "/main-toolbar");
-	g_return_val_if_fail (toolbar != NULL, NULL);
-
-	item = gtk_toolbar_get_nth_item (GTK_TOOLBAR (toolbar), 0);
-	g_return_val_if_fail (item != NULL, NULL);
-	g_return_val_if_fail (E_IS_MENU_TOOL_BUTTON (item), NULL);
-
-	return e_menu_tool_button_get_prefer_item (E_MENU_TOOL_BUTTON (item));
-}
-
-/**
- * e_shell_window_set_toolbar_new_prefer_item:
- * @shell_window: an #EShellWindow
- * @prefer_item: prefer-item name to be set
- *
- * Sets prefer item on the New button for current view.
- *
- * Since: 3.4
- **/
-void
-e_shell_window_set_toolbar_new_prefer_item (EShellWindow *shell_window,
-                                            const gchar *prefer_item)
-{
-	GtkWidget *toolbar;
-	GtkToolItem *item;
-
-	g_return_if_fail (shell_window != NULL);
-	g_return_if_fail (E_IS_SHELL_WINDOW (shell_window));
-
-	toolbar = e_shell_window_get_managed_widget (shell_window, "/main-toolbar");
-	g_return_if_fail (toolbar != NULL);
-
-	item = gtk_toolbar_get_nth_item (GTK_TOOLBAR (toolbar), 0);
-	g_return_if_fail (item != NULL);
-	g_return_if_fail (E_IS_MENU_TOOL_BUTTON (item));
-
-	e_menu_tool_button_set_prefer_item (E_MENU_TOOL_BUTTON (item), prefer_item);
-}
-
-/**
  * e_shell_window_register_new_item_actions:
  * @shell_window: an #EShellWindow
  * @backend_name: name of an #EShellBackend
diff --git a/shell/e-shell-window.h b/shell/e-shell-window.h
index abd940feb0..b96d2f6df5 100644
--- a/shell/e-shell-window.h
+++ b/shell/e-shell-window.h
@@ -134,11 +134,6 @@ gboolean	e_shell_window_get_toolbar_visible
 void		e_shell_window_set_toolbar_visible
 						(EShellWindow *shell_window,
 						 gboolean toolbar_visible);
-const gchar *	e_shell_window_get_toolbar_new_prefer_item
-						(EShellWindow *shell_window);
-void		e_shell_window_set_toolbar_new_prefer_item
-						(EShellWindow *shell_window,
-						 const gchar *prefer_item);
 
 /* These should be called from the shell backend's window_created() handler. */