C# RichTextBox控件 滚动条 自动移至 最后一条记录处

void SetrichTextBox(string value)
        {
            
            if (RecRichTextBox.InvokeRequired)
            {
                SetrichTextBox1_Callback d = new SetrichTextBox1_Callback(SetrichTextBox);
                RecRichTextBox.Invoke(d, value);
            }
            else
            {
                if (RecRichTextBox.Lines.Length >100)
                { RecRichTextBox.Clear(); }

                //========richtextbox滚动条自动移至最后一条记录
                //让文本框获取焦点   
                RecRichTextBox.Focus();
                //设置光标的位置到文本尾   
                RecRichTextBox.Select(RecRichTextBox.TextLength, 0);
                //滚动到控件光标处   
                RecRichTextBox.ScrollToCaret();
                RecRichTextBox.AppendText(value);
            }
        }