[evolution] Fix a reference counting issue in EShellTaskbar.

[Matthew Barnes <mbarnes src gnome org>]

commit 5493a2373b76e9eee14662a41a16ebb7615be6da
Author: Matthew Barnes <mbarnes redhat com>
Date:   Thu Sep 3 16:34:07 2009 -0400

    Fix a reference counting issue in EShellTaskbar.

 shell/e-shell-taskbar.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)
---
diff --git a/shell/e-shell-taskbar.c b/shell/e-shell-taskbar.c
index 61f27fb..c3d89d7 100644
--- a/shell/e-shell-taskbar.c
+++ b/shell/e-shell-taskbar.c
@@ -33,6 +33,10 @@ struct _EShellTaskbarPrivate {
 
 	gpointer shell_view;  /* weak pointer */
 
+	/* Keep a reference to the shell backend since
+	 * we connect to its "activity-added" signal. */
+	EShellBackend *shell_backend;
+
 	GtkWidget *label;
 	GtkWidget *hbox;
 
@@ -166,6 +170,14 @@ shell_taskbar_dispose (GObject *object)
 		priv->shell_view = NULL;
 	}
 
+	if (priv->shell_backend != NULL) {
+		g_signal_handlers_disconnect_matched (
+			priv->shell_backend, G_SIGNAL_MATCH_DATA,
+			0, 0, NULL, NULL, object);
+		g_object_unref (priv->shell_backend);
+		priv->shell_backend = NULL;
+	}
+
 	if (priv->label != NULL) {
 		g_object_unref (priv->label);
 		priv->label = NULL;
@@ -206,6 +218,10 @@ shell_taskbar_constructed (GObject *object)
 	shell_view = e_shell_taskbar_get_shell_view (shell_taskbar);
 	shell_backend = e_shell_view_get_shell_backend (shell_view);
 
+	/* Keep a reference to the shell backend so we can
+	 * disconnect the signal handler during dispose(). */
+	shell_taskbar->priv->shell_backend = g_object_ref (shell_backend);
+
 	g_signal_connect_swapped (
 		shell_backend, "activity-added",
 		G_CALLBACK (shell_taskbar_activity_add), shell_taskbar);