and more specifically this commit
https://github.com/chrisboyle/sgtpuz...c25738cfe0b126
which is the first "final" commit from about 4 years ago and /probably/ contains most of the major changes required to make it go the new platform.
It should be noted that in fact this cited work is more about adding java support than tweaking the gtk guts. so... not necessarily actually any help...
Note the following link will /probably/ become out of date if new commits are applied...
https://github.com/chrisboyle/sgtpuz...master?page=14
(however it's been a year since the last commit so... should be okay)