Moving NSRulerMarker and the document view

FROM : Benjamin Dunton
DATE : Tue Aug 01 00:13:57 2006

I am having a bear of a problem reproducing the timeline 
functionality seen in garageband.  When the playhead starts it moves 
across the ruler view until it gets to the middle, the scroll view 
then begins to slide the document view underneath, giving the 
impression of the playhead staying in the middle.

I can get the document view to scroll, but I can not get the playhead 
to stay in the middle.  Any ideas?

Ben