So, following the Jessie release, and after a quick approval by the release team for the 4.12 transition, we've uploaded Xfce 4.12 to sid and have asked the RT to schedule the relevant binNMUs for the libxfce4util and xfce4-panel reverse dependencies.

It went apparently well (besides some hickups here and there, lilke some lag on sparc, and some build-failulres on hurd). So Xfce 4.12 is now in sid, and should migrate to Stretch in the following weeks, provided nothing release critical is found.