I'm not sure if this is the same as what you're talking about, but the UltraNav on my T520 has an option for scrolling type 'auto-select'. For me it doesn't do what is desired in the OP of this thread. If I set the scrolling type to smooth, and the functionality to scrolling, it just acts like a middle click. For programs like chrome and firefox this is manageable as they bring up the scroller. For programs like notepad, it does nothing (it cannot scroll).