Created attachment 769042 [details]
Bundle with test project, video describing procedure and gdb log

After performing certain actions in code editor QtCreator crashes with
segmentation fault error. Crashes are reproducible, as in repeating certain
action on certain project in exactly the same order always leads to
Segmentation fault.

Actions required for crash are really precise (eg. putting cursor in different
place, editing different lines or performing other action meanwhile may not
lead to crash).

Exact order of actions leading to crash has been recorded and added as
attachment. Transcript:
1. open QtCreator
2. open project
3. open second window and split both windows side-by-side
4. open mess_core.h few times 
5. remove lines 16-10 from mess_core.h

Crashes have been noticed also in other cases with similar characteristics
(certain exact order of actions results in segmentation fault) although I
didn't notice any particular pattern. Crashes are quite frequent for regular
work. I've been able to cause crash during regular work every few hours on
average.

This is clean OpenSUSE 42.3 installation in VirtualBox, created few days ago
after issue has been initially noticed in Tumbleweed.