I searched to see if anyone else has posted anything about it and was unable to find anything.
When I add a document such as a word document and go it the integrated preview window and click the preview button it opens the document just fine and I can read it in the integrated preview box. When I click the box area in order to scroll, the box maximizes overtaking the complete window of the brain 9 and the only way I have been able to return to normal view is by "un-maximizing" (restore) the brain. If the brain window is not maximized when this happens, then maximizing it will restore the plex view. Intuitively, I try to use escape to exit the maximized view and it does nothing.