import javax.swing.undo.UndoManager;

static <A extends JTextComponent> A jenableUndoRedo(A textcomp) {
  final new UndoManager undo;
  textcomp.getDocument().addUndoableEditListener(new UndoableEditListener() {
    public void undoableEditHappened(UndoableEditEvent evt) {
      undo.addEdit(evt.getEdit());
    }
  });
  
  textcomp.getActionMap().put("Undo", abstractAction("Undo", r {
    if (undo.canUndo()) undo.undo()
  }));
  textcomp.getActionMap().put("Redo", abstractAction("Redo", r {
    if (undo.canRedo()) undo.redo()
  }));
  textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Z"), "Undo");
  textcomp.getInputMap().put(KeyStroke.getKeyStroke("control Y"), "Redo");
  ret textcomp;
}