private void deactivateBlock(){
  if ((mBlockListener != null) && (block != null)) {
    block.removePropertyChangeListener(mBlockListener);
  }
  mBlockListener=null;
}

private void deactivateBlock ( ) { if ( ( mBlockListener != null ) && ( block != null ) ) { block . removePropertyChangeListener ( mBlockListener ) ; } mBlockListener = null ; }
deactivate block listener for redraw of panels and update of memories on change of state
