Scrollbar in scrollpanel stops working when autoscroll is on

I am using NIFTY to build my GUI and I have a chatbox where the user can see the converstations:

           [java] <control name="scrollPanel" id="scroll_panel" valign="bottom" align="center" x="5%" y="23%" width="60%" height="70%" horizontal="false" vertical="true" autoScroll="bottom" >
                <text text=""  id="txtDialogue" width="100%" height="100%" focusable="false" wrap="true" textHAlign="left" textVAlign="top" align="left" font="fonts/comicbook_25.fnt"/>

As you can see the autoscroll is on to make sure that the latest text is displayed. But because of this the scrollbar doesn’t work anymore. (So I can’t go up myself and see previously typed text). Is there a way to circumvent this problem ?

Also, is it possible to change the speed of the scrolling text ?