[evolution-data-server] Fixes #603557 - evoluton will crash when settingup LDAP address book if A11Y is enabled.

[Jedy Jedy Wang <jedywang src gnome org>]

commit b8a5a6c816cc7beef29247ae079c5fccec2328f4
Author: Wang Xin <jedy wang sun com>
Date:   Mon Dec 21 11:27:16 2009 +0800

    Fixes #603557 - evoluton will crash when settingup LDAP address book if A11Y is enabled.

 libedataserverui/e-source-selector.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/libedataserverui/e-source-selector.c b/libedataserverui/e-source-selector.c
index e92279c..e7789fd 100644
--- a/libedataserverui/e-source-selector.c
+++ b/libedataserverui/e-source-selector.c
@@ -464,6 +464,10 @@ toggle_cell_data_func (GtkTreeViewColumn *column,
 	gpointer data;
 
 	gtk_tree_model_get (model, iter, 0, &data, -1);
+	if (data == NULL) {
+		g_object_set (renderer, "visible", FALSE, NULL);
+		return;
+	}
 
 	if (E_IS_SOURCE_GROUP (data)) {
 		g_object_set (renderer, "visible", FALSE, NULL);
@@ -490,6 +494,10 @@ text_cell_data_func (GtkTreeViewColumn *column,
 	gpointer data;
 
 	gtk_tree_model_get (model, iter, 0, &data, -1);
+	if (data == NULL) {
+		g_object_set (renderer, "visible", FALSE, NULL);
+		return;
+	}
 
 	if (E_IS_SOURCE_GROUP (data)) {
 		g_object_set (renderer,