Bug 740471 - Applying payment to invoice Segmentation fault

Stop listening for gui update events while on the way out
(after the ok button was pressed).

src/business/business-gnome/dialog-payment.c

@@ -649,6 +649,17 @@ gnc_payment_ok_cb (GtkWidget *widget, gpointer data)
      * and amount so we can proceed with the payment.
      * Note: make sure it's called before all entry points to this function !
      */
+
+    /* We're on our way out, stop watching for object changes that could
+     * trigger a gui refresh. Without this the gui suspend/resume
+     * pair could still trigger a gui update on the payment dialog
+     * before we close it. This is undesired because the lots may be in
+     * an inconsistent state until after all events are handled. So
+     * the gui refresh may result in a crash.
+     * See https://bugzilla.gnome.org/show_bug.cgi?id=740471
+     */
+    gnc_gui_component_clear_watches (pw->component_id);
+
     gnc_suspend_gui_refresh ();
     {
         const char *memo, *num;