Bigger textbox scrollbar?

[N1c0_ds]

I use 20 pixel scrollbars in my application to make finger navigation easier. Attaching a scrollbar control to a textbox is easy, but if the user scrolls with TouchFlow or navigation keys, the scrollbar will not adjust to the position of the textbox. Is there a way to change this?

OR

Is there a way to change the scrollbar size on the textbox?


Thanks!