private void CreateFloorBelow()
 {
     ComboBoxItem_Z item = m_comboBox_z.Items[m_comboBox_z.Items.Count - 2] as ComboBoxItem_Z;
     int newFloor = (item == null) ? -1 : item.Z - 1;
     item = new ComboBoxItem_Z(newFloor);
     m_comboBox_z.Items.Insert(m_comboBox_z.Items.Count - 1, item);
     m_comboBox_z.SelectedItem = item;
 }
 private void CreateFloorAbove()
 {
     ComboBoxItem_Z item = m_comboBox_z.Items[1] as ComboBoxItem_Z;
     int newFloor = (item == null) ? 0 : item.Z + 1;
     item = new ComboBoxItem_Z(newFloor);
     m_comboBox_z.Items.Insert(1, item);
     m_comboBox_z.SelectedItem = item;
 }