Separate navigation bar and page content into separate scroll elements

[raymondberg]

Problem: When I scroll in large content, the tree on the left disappears. When I have a long tree the page content disappears when I scroll. They should scroll independently.

Separate the navigation side bar and the substantive pages into individually scrollable panes. When clicking on a different entry in the navigation bar pane, the view of the substantive page pane will always display at the top. (Currently, when clicking on a entry a the bottom of the navigation side bar, the user needs to scroll to the top of the page if they want to see the beginning of the substantive entry.)