[Dr.CustUmz]

Updated with support for per forums as well as per thread.

Explanation of how it works:
You set a custom header for a section within the forum manager.
All child forums will also get this header UNLESS you define one for them specifically for a child forum. If a thread within those forums has a custom header, it will override any previous set headers.

Modify forum headers via the forum manager, modify thread headers pretty much anywhere you edit a thread (new thread, edit 1st post, admin edit thread).

TO DO:
usergroup permissions to be able to apply custom headers.
header editor on forumdisplay pages.