public void undoableEditHappened(UndoableEditEvent e){
  m_Undo.addEdit(e.getEdit());
  m_UndoAction.updateUndoState();
  m_RedoAction.updateRedoState();
}

public void undoableEditHappened ( UndoableEditEvent e ) { m_Undo . addEdit ( e . getEdit ( ) ) ; m_UndoAction . updateUndoState ( ) ; m_RedoAction . updateRedoState ( ) ; }
gets called when an undoable event gets triggered .
