How to achieve independent left and right panes?

[Curt]

I wonder if any plug-ins provide this capability, hopefully the plug-in vendors are reading this :-). Or if there's another way, great. Here's the simple behavior I want:

Suppose you have a pervasive pane on the left side of a page that provides a pervasive hierarchy of pages. Pretty classic. Accordingly, the pane on the right displays the content of the selected hierarchy branch. The behavior I want is that: 1) As I click on a branch in the left pane, the pane remains static (does not reset back to the top) and only the branch I've selected now becomes the bolded branch. That should be the only dynamic that occurs when I select a branch. 2) The content within the right pane is reflective of the branch I've selected, AND I can scroll through that content without the left pane being affected. That is, I can scroll up/down through the left pane (the tree), and scroll up/down through the content of the right pane, without either of them affecting the other. Any thoughts on this?