private void RedoButton_Click(object sender, EventArgs e)
        {
            if (canvas.UndoRedoIndex + 1 == canvas.UndoRedoList.Count)
            {
                RedoButton.Enabled = false;
            }
            else
            {
                canvas.RedoLastAction();
            }

            UndoButton.Enabled = true;
            this.Refresh();
        }