not in testing, not in unstable.
===
Please feel free to respond to this email if you don't understand why
your files were rejected, or if you upload new files which address our
concerns.
What specifically are you concerned with? These subpackages *cannot exist*
in unstable/testing because libwebkitgtk-dev no longer exists there. They
need to be added back in for a stretch backport because they exist in the
regular stretch version of wxwidgets3.0 (and thus could cause breakage for
users who install the backported version of wxwidgets3.0).
This bpo9~2 change essentially undoes this commit:
https://salsa.debian.org/freewx-team/wx/commit/741448ae05f80c380c1d820d6671f0c4b5d2bdfb