TYPO3 Core

Problem:
if nav_frame and list_frame are reloaded at exactly the same time the queued flashmessages show up in both frames

Solution:
prevent the nav_frame from displaying flahmessages by introducing a new member var to template.php which if unset, prevents the nav_frame (and also the file_nav_frame) from rendering flashmessages

(issue imported from #M12188)