I have tried to use xe:pagerSaveState to preserve view state when user opens the document from the view panel and then close it and returns back to the view. Although it really works in case when user clicks a button that (besides other things) closes the document and opens the view again it does NOT work in cases when a user simply clicks on back button provided by the browser.
It is clear that the problem stems from the fact that viewStateBean.restoreState = true is not set. I cannot find any suitable event that would assure that this is executed every time user hits back button provided by the browser.