Hi Vlad, I'm considering filing a "jessie-pu" bug on release.debian.org with patches for the serious bugs you mention in this thread. I think it will be much easier to get acceptance from the Stable Release team for that than to actually get the complete 3.14.x bugfix release in. Then we can paste the entire readable debdiff in the bug report for them to review it.
Let me know what you think about it. I've started working on it here: https://github.com/rubund/gtk-bugfix/tree/master I'm not a maintainer of GTK, just a guy like you wanting to get some very important bug fixes into jessie. We need a few people to extensively test the package before filing the "jessie-pu" bug. Best regards Ruben