How do I split screens in 2.5?

In 2.4x one clicks the window divider with the middle mouse button to split or join scenes, how does one do that in 2.5? For that matter how do I access the preferences in 2.5?
Preferences are in File / User Preferences
I’d recommend doing forum searches before asking questions because there are countless threads discussing the pros and cons of the new way of splitting windows.
Alsoi getting started with blender 2.5