This is copied from an email from Dimitri John Ledkov
<dimitri.j.ledkov@intel.com> sent to gnupg-devel on Nov. 3rd, 2014:
This patch improves compatibility with Gtk+3, without removing support
for any of the currently supported Gtk+2 versions.
Looking at the git repository for the pinentry this patch has not been applied.
Is work towards improving Gtk+3 support not welcomed?
This is not a complete port and further changes would be needed to
support Gtk+3.