private void RemoveSuburbFromPreferred()
 {
     if (SelectedSuburbToRemove != null)
     {
         UnselectedSuburbList.Add(SelectedSuburbToRemove);
         ContractorPreferredSuburbList.Remove(SelectedSuburbToRemove);
         SelectedSuburbToAdd    = null;
         SelectedSuburbToRemove = null;
     }
 }
 private void AddSuburbToPreferred()
 {
     if (SelectedSuburbToAdd != null)
     {
         ContractorPreferredSuburbList.Add(SelectedSuburbToAdd);
         UnselectedSuburbList.Remove(SelectedSuburbToAdd);
         SelectedSuburbToAdd    = null;
         SelectedSuburbToRemove = null;
     }
 }