That will be a problem for the current development of APB-IE. It will be of little use in term of compatibility for IE12's new extension engine. I've not look at the codes for ABP-IE, nor will I have the time to, so I'll just throw this question out there blindingly. Is it possible to re-purpose ABP-IE into a system-wide HTTP/HTTPS proxy filtering engine? Something like that of Adguard or Adfender.
Edited: Also a little interesting tidbits, the IE team actually considered adopting Webkit for future IEs before saying nope because of of legacy 'compatibility'. They pointed out as specifically as the "F1" helper pages as one of the legacies. Yup, those little help pages are preventing IE to adopt Webkit
