this?
viewtopic.php?f=461&t=2482306&sid=ac532 ... #p15071731
when I tried it it did not work and then I did not try it again.
With your listener, I use one less core ... now I'll try again
Edit:
work fine... you also save the use of 'core.page_header_after' .
Replaced on github and in the validation queue.