Make tracker grid scrollbox follow selection

[SuperDisk]

Q: My monitor shows 42 rows of the pattern grid. When I press the down arrow to move the cursor below the visible portion of the pattern, the cursor moves past row 42 into the other 20-odd rows of the pattern, yet the pattern doesn't scroll along with it. In order to bring the row under the cursor back into view, I have to move my hand to the mouse, move the mouse pointer to the scroll bar, and use the scroll wheel there. How do I make the pattern scroll as I reach the bottom of the view, the way it works in every text editor and other tracker that I have used?