Yad finally got into sid/stretch. It is installable in jessie. However, it is an old version (0.27) and gtk3-only (requiring gtk3 libs + baggage). The slavino.sk version which most of us have been using is gtk2 but still version 0.27.
The current upstream version is 0.33.1 .. It makes dpkg-buildpackage puke but that is fixed in svn (r917)
For anyone interested I posted sources and (gtk2) debs here: http://exegnulinux.net/refracta/experimental/yad/
If you want to build yourself, the debian.tar.xz posted there can be modified to suit. Get the latest svn from https://sourceforge.net/p/yad-dialog/code/HEAD/tree/