Hi,
it was an update from V7.5.6p2 to 7.6.2
Yes, it is /includes/header.php and the code I use in it was running up to 7.5.6 without a change. It should pull the wrapper to put my own header in a box. Long time ago I got a sample for it here in the forums somewhere. I will read your link and maybe find out to pull the wrapper again.
Regards
Zarzal