static int CompareTasksSortFunc(Gtk.TreeModel model,
Gtk.TreeIter a,
Gtk.TreeIter b)
{
ITask taskA = model.GetValue (a, 0) as ITask;
ITask taskB = model.GetValue (b, 0) as ITask;
if (taskA == null || taskB == null)
return 0;
return (taskA.CompareTo (taskB));
}