initialize value to prevent compilation warning

Change-Id: Iffd9e296e1e089bf1cc248d5d1ab9f142ba7dfb6
Tuleap: #211
diff --git a/src/utils/models.cpp b/src/utils/models.cpp
index 0346ddd..1052bb1 100644
--- a/src/utils/models.cpp
+++ b/src/utils/models.cpp
@@ -119,7 +119,7 @@
         if (GTK_IS_TREE_MODEL_FILTER(filter_model))
             model = gtk_tree_model_filter_get_model(GTK_TREE_MODEL_FILTER(filter_model));
 
-        gboolean valid;
+        gboolean valid = FALSE;
         if (GTK_IS_Q_TREE_MODEL(model)) {
             valid = gtk_q_tree_model_source_index_to_iter(
                 GTK_Q_TREE_MODEL(model), idx, &new_iter);