class MyContextMenuStrip : ContextMenuStrip
{
    private C1Editor _owner;
    private ToolStripMenuItem _btnUndo, _btnRedo;
            
    public MyContextMenuStrip(C1Editor editor)
    {
        // save reference to parent control
        _owner = editor;
            
        // create menu items
        _btnUndo = (ToolStripMenuItem)Items.Add("Undo");
        _btnUndo.ShortcutKeys = Keys.Control | Keys.Z;
        _btnRedo = (ToolStripMenuItem)Items.Add("Redo");
        _btnRedo.ShortcutKeys = Keys.Control | Keys.Y;
    }
            
    protected override void OnItemClicked(ToolStripItemClickedEventArgs e)
    {
        Close();
            
        if (e.ClickedItem == _btnUndo)
            _owner.Undo();
        else if (e.ClickedItem == _btnRedo)
            _owner.Redo();
        base.OnItemClicked(e);
    }
            
    protected override void OnOpening(System.ComponentModel.CancelEventArgs e)
    {
        _btnUndo.Enabled = _owner.CanUndo;
        _btnRedo.Enabled = _owner.CanCut;
        base.OnOpening(e);
    }