yes Munair, I have seen a number of segv on exit when testing my app on GTK3, I noted in a bug report (on another issue) that it seemed to happen to me about one in five times I started and stopped even simple apps.
I gave up on GTK3 and now recommend QT5 on newer Linux OS.
Some of the GTK3 LCL code is using deprecated GTK3 interfaces, particularly around scaling and showing windows, getting monitor sizes, resolutions etc. If they cannot keep the GTK3 interface stable, its all just too hard.
QT5 seems pretty good on recently released linux, pretty poor on older ones (such as Ubuntu LTS).
Davo