c# winform richtextbox控制每行颜色 + 滚动条始终滚动到最底部

        /// <summary>
        /// 输出
        /// </summary>
        /// <param name="content"></param>
        /// <param name="color"></param>
        private void Output(string content, Color color)
        {
            Invoke(new MethodInvoker(delegate ()
            {
                //超出一万行，清空
                this._lines++;
                if (this._lines > 10000)
                {
                    this.txtOutput.Text = string.Empty;
                    this._lines = 1;
                }

                content += Environment.NewLine;
                this.txtOutput.SelectionColor = color;//设置文本颜色
                this.txtOutput.AppendText(content);//输出文本，换行

                this.txtOutput.SelectionStart = this.txtOutput.Text.Length;//设置插入符位置为文本框末
                this.txtOutput.ScrollToCaret();//滚动条滚到到最新插入行
            }));
        }