The
clicking behaviour introduced by commit#fb0a13b has confused many
users in the past 2 years. By reverting the commit, the patch
makes the primary button clicking behave as consistent as most
users has been used to (bgo#758065 bsc#1057471).

Some ideas to change this was raised up in the quoted bugs and the following declining of patch, while we did not see a clear trend from upstream to improve this in short term

https://mail.gnome.org/archives/gtk-devel-list/2017-October/msg00002.html

Still we will be working in upstream with more easily "merge-able" improvements on this. (forwarded request 533214 from yfjiang)