n = false);
        <span style="color:navy"><b>PROCEDURE</b></span> undo;
        <span style="color:navy"><b>PROCEDURE</b></span> redo;
        <span style="color:navy"><b>PROPERTY</b></span> canundo: boolean <span style="color:navy"><b>READ</b></span> getcanundo;
        <span style="color:navy"><b>PROPERTY</b></span> canredo: boolean <span style="color:navy"><b>READ</b></span> getcanredo;
        <span style="color:navy"><b>PROPERTY</b></span> maxcount <span style="color:navy"><b>DEFAULT</b></span> defa