[goffice] Canvas: clean up disposal of GocItems a bit.

[Morten Welinder <mortenw src gnome org>]

commit a5834f27d1d367862480f5b4a1db6d2ee9433eef
Author: Morten Welinder <terra gnome org>
Date:   Mon Mar 17 08:49:17 2014 -0400

    Canvas: clean up disposal of GocItems a bit.

 ChangeLog                   |    8 ++++++++
 goffice/canvas/goc-canvas.c |    8 +-------
 goffice/canvas/goc-item.c   |   19 +++++++++++++++++++
 3 files changed, 28 insertions(+), 7 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 2aa0946..c07f0b1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2014-03-17  Morten Welinder  <terra gnome org>
+
+       * goffice/canvas/goc-canvas.c (goc_canvas_dispose): Dispose of
+       ->root instead of simply clearing it.
+
+       * goffice/canvas/goc-item.c (goc_item_dispose): Dispose of style
+       context, if we have one.
+
 2014-03-16  Morten Welinder  <terra gnome org>
 
        * goffice/canvas/goc-polyline.c (goc_polyline_distance): Don't
diff --git a/goffice/canvas/goc-canvas.c b/goffice/canvas/goc-canvas.c
index cf9a26b..d889b03 100644
--- a/goffice/canvas/goc-canvas.c
+++ b/goffice/canvas/goc-canvas.c
@@ -250,13 +250,7 @@ static void
 goc_canvas_dispose (GObject *obj)
 {
        GocCanvas *canvas = GOC_CANVAS (obj);
-       GtkStyleContext *context = goc_item_get_style_context (GOC_ITEM (canvas->root));
-       goc_group_clear (canvas->root);
-       /* we need to set the parent context to NULL for root before unrefing it
-        * because Gtk+ calls the "changed" signal when the parent is set to
-        * NULL from gtk_style_context_finalize(), and as the ref_count is already
-        * NULL, this fires criticals. */
-       gtk_style_context_set_parent (context, NULL);
+       g_object_run_dispose (G_OBJECT (canvas->root));
        parent_klass->dispose (obj);
 }
 
diff --git a/goffice/canvas/goc-item.c b/goffice/canvas/goc-item.c
index acff12d..a47b642 100644
--- a/goffice/canvas/goc-item.c
+++ b/goffice/canvas/goc-item.c
@@ -24,6 +24,11 @@
 #include <gsf/gsf-impl-utils.h>
 #include <glib/gi18n-lib.h>
 
+#ifdef GOFFICE_WITH_GTK
+static void cb_parent_changed (const GocItem *item);
+#endif
+
+
 /**
  * SECTION:goc-item
  * @short_description: Base canvas item.
@@ -213,6 +218,8 @@ static void
 goc_item_dispose (GObject *object)
 {
        GocItem *item = GOC_ITEM (object);
+       GtkStyleContext *context;
+
        if (item->canvas) {
                if (item->canvas->last_item == item)
                        item->canvas->last_item = NULL;
@@ -225,6 +232,18 @@ goc_item_dispose (GObject *object)
        if (item->parent != NULL)
                goc_group_remove_child (item->parent, item);
 
+#ifdef GOFFICE_WITH_GTK
+       context = g_object_get_qdata (G_OBJECT (item), quark_style_context);
+       if (context) {
+               g_signal_handlers_disconnect_by_func
+                       (object, G_CALLBACK (cb_parent_changed), NULL);
+#ifdef HAVE_GTK_STYLE_CONTEXT_SET_PARENT
+               gtk_style_context_set_parent (context, NULL);
+#endif
+               g_object_set_qdata (object, quark_style_context, NULL);
+       }
+#endif
+
        item_parent_class->dispose (object);
 }