[devhelp/wip/swilmet/various-code-improvements: 1/3] book-tree: be able to jump back to the currently selected item

[Sébastien Wilmet <swilmet src gnome org>]

commit bd3cd7faeae2536e474dfed086c774cb1ce54d40
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Wed Nov 11 18:04:15 2015 +0100

    book-tree: be able to jump back to the currently selected item
    
    It's already done for the search hitlist in DhSidebar. So do it also for
    the book tree, for consistency and because it's something useful.

 src/dh-book-tree.c |   47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 47 insertions(+), 0 deletions(-)
---
diff --git a/src/dh-book-tree.c b/src/dh-book-tree.c
index fbc3ef1..89be7d8 100644
--- a/src/dh-book-tree.c
+++ b/src/dh-book-tree.c
@@ -698,16 +698,63 @@ dh_book_tree_constructed (GObject *object)
         G_OBJECT_CLASS (dh_book_tree_parent_class)->constructed (object);
 }
 
+/* Make it possible to jump back to the currently selected item, useful when the
+ * html view has been scrolled away.
+ */
+static gboolean
+dh_book_tree_button_press_event (GtkWidget      *widget,
+                                 GdkEventButton *event)
+{
+        DhBookTree *tree = DH_BOOK_TREE (widget);
+        DhBookTreePrivate *priv = dh_book_tree_get_instance_private (tree);
+        GtkTreePath *path;
+
+        gtk_tree_view_get_path_at_pos (GTK_TREE_VIEW (tree),
+                                       event->x, event->y,
+                                       &path, NULL, NULL, NULL);
+
+        if (path != NULL) {
+                GtkTreeIter iter;
+                DhLink *link;
+
+                gtk_tree_model_get_iter (GTK_TREE_MODEL (priv->store), &iter, path);
+
+                gtk_tree_model_get (GTK_TREE_MODEL (priv->store),
+                                    &iter,
+                                    COL_LINK, &link,
+                                    -1);
+
+                if (link != NULL &&
+                    link != priv->selected_link) {
+                        priv->selected_link = link;
+                        g_signal_emit (tree, signals[LINK_SELECTED], 0, link);
+                }
+
+                gtk_tree_path_free (path);
+        }
+
+        /* Always propagate the event so the tree view can update
+         * the selection etc.
+         */
+        if (GTK_WIDGET_CLASS (dh_book_tree_parent_class)->button_press_event == NULL)
+                return GDK_EVENT_PROPAGATE;
+
+        return GTK_WIDGET_CLASS (dh_book_tree_parent_class)->button_press_event (widget, event);
+}
+
 static void
 dh_book_tree_class_init (DhBookTreeClass *klass)
 {
         GObjectClass *object_class = G_OBJECT_CLASS (klass);
+        GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
         object_class->dispose = dh_book_tree_dispose;
         object_class->get_property = dh_book_tree_get_property;
         object_class->set_property = dh_book_tree_set_property;
         object_class->constructed = dh_book_tree_constructed;
 
+        widget_class->button_press_event = dh_book_tree_button_press_event;
+
         g_object_class_install_property (object_class,
                                          PROP_BOOK_MANAGER,
                                          g_param_spec_object ("book-manager",