Maintain scrolling between two richtextbox

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VB

Windows

C#3.5

Hi,

I am making typing tutor Like Application In C# windows Application. I have two richtextbox with following name(1. UserTXT and 2. SystemTXT).

I have done every thing almost But I am getting issue while maintain scroll Between then.

SystemTXT is upper on screen and display test content to user and in UserTxt user can type the word to see from SystemTXT. But when if SystemTxt is greater then his height then its display scrolling and I want When user typing in UserTXt then automatic scroll is start if User goes back then scrolling reset and if user type forward the hide txt display automatic scroll. Please any one can help me.

Please see the screenshot for more understanding.

<img src="http://www.webunitech.com/txtscroll.jpg"/>

Thanks
Ram Kumar

What I have tried:

SystemTXT is upper on screen and display test content to user and in UserTxt user can type the word to see from SystemTXT. But when if SystemTxt is greater then his height then its display scrolling and I want When user typing in UserTXt then automatic scroll is start if User goes back then scrolling reset and if user type forward the hide txt display automatic scroll. Please any one can help me.