I find myself going back and forth a lot in large trees (a few pages with only the essentials expanded), but between a relatively small number of nodes at a time, mostly checking consistency between different characters POV chapters when they overlap, or checking background information when writing for a character. This searching gets very tedious, compared to cycling between a set of tabs.
I would imagine this requires the addition of keys/buttons to create/destroy/cycle tabs, with no need for the tabs to be persistent, and the only necessary state is which node/position is currently being viewed in a given tab. To limit the amount of work, it could probably be done more like a bookmark (i.e. cycling equates to storing the current tab's node, then loading the prev/next tab's node and sending the position to the rich text edit control, without introducing multiple edit controls to implement the feature).
As a sidebar, I welcome the suggested addition of simple tables and would suggest a checkbox to have the scrollbar always on to avoid annoying reflow.
Kind regards.