Thanks for the replies and apologies for the late response. I'm having a very busy period. I have in the meantime submitted a bug report: https://bugreports.qt.io/browse/QTBUG-73177
Qt 5.12.1 just got released, can you check again if you still have the same problem ?
Yes, I did check 5.12.1 and nothing has changed. I've updated my bug report accordingly.
d_cancel is a race condition, change its type to std::atomic_bool
What I suspect is happening is that this intersect check is not working correctly when you disable the scrollbars
Thanks, I just wrote that little example code quickly and indeed, d_cancel could lead to problems (though not very likely). rest assured, in the actual project where I'm seeing this problem, the equivalent bool is already a std::atomic_bool.
Thanks for the hint as to where the problem is, I will try to investigate.
I have tried to install the debug packages of qt on my machine, but the easiest way to do so, they overwrite the normal packages and make my desktop unusable (since I'm running KDE which uses qt). So I need to figure out how to install a second, separate version or try to debug on a different (virtual) machine. Either way, just getting it set up will take more time than i have had lately. To be continued.