private void comboBoxModel_SelectionChanged(object sender, SelectionChangedEventArgs e)
 {
     if (null != comboBoxModel.SelectedItem)
     {
         selectedModel = (RevitDocumentProperties)comboBoxModel.SelectedItem;
         DisplayFloorInfo();
     }
 }
 private void comboBoxModel_SelectionChanged(object sender, SelectionChangedEventArgs e)
 {
     try
     {
         if (null != comboBoxModel.SelectedItem)
         {
             selectedModel = (RevitDocumentProperties)comboBoxModel.SelectedItem;
             DisplayRoomInfo();
         }
     }
     catch (Exception ex)
     {
         MessageBox.Show("Failed to change the source model.\n" + ex.Message, "Source Model Changed", MessageBoxButton.OK, MessageBoxImage.Warning);
     }
 }