When scrolling a page up or down using fn ↑ and fn ↓ in a text editor, the editor jumps immediately to the next page. This is confusing when reading structured documents such as source code (programming). Is there a way to get OS X to smoothly scroll down one page, as if I would have used the trackpad?
Smooth scrolling is dependent on the application. TextEdit does offer smooth scrolling when paging through a long document. BBEdit 11 does not.
Apple's developer WWDC 2013 talk below is aimed at helping developers to achieve this:
Creating a responsive app requires fast drawing and smooth scrolling. Discover techniques to optimize drawing, find out best practices for handling layers, and learn how to combine those techniques with new features to achieve smooth scrolling.
If possible, provide feedback to the editor's developer that you value this behaviour.