With TinkerTool I changed a system-wide preference that all scroll- 
bars show two arrows at each end. Could be this changes the behaviour  
– or it's a Tiger (10.4.11) feature!

>
>
>> Dragging at scroll-bar downwards scrolls the buffer until
>> all its contents is scrolled away.
>
> This is currently the std behavior of scrollbars in the NS port.   
> Do other emacsen behave differently?


It's not the standard behaviour in other Cocoa applications (in  
Terminal, Mail, Preview the scroll-bar stops and I see the bottom of  
the "buffer" at the window's bottom), this looks more like copying  
the bad manners of GTK.

--
Greetings

   Pete

To most people solutions mean finding the answers. But to chemists  
solutions are things that are still all mixed up.