Wixi currently colapses category tree with every click on save button.
I think this is very annoying when you do rearrage or work with
several pages.

A method of reducing auto-collapse would be:
## Before collapse(save button) ##
- remember what categories are rolled and unrolled.
--- Do modifications, incl page and category renaming and all else ---
## go through the previously saved category tree ##
  -- remove all category entries on cats  that were removed.
  -- mark as unrolled any category that got renamed(has new,
unmatching name).
- autounroll categories that were remembered.

This is only my opinion.
Also to my information when you rename category, it does not trigger
category tree collapse.
Also check my other bug report, as sometimes renamed pages do not get
their links updated or do not get into right category. Only after you
push save button once(sometimes twice). This may be related to not
updating tree except on save button click.

Shin.