These steps reliably reproduce the issue for me with a MacBook Pro (15-inch, 2018)
- Use the laptop in 'clamshell mode', with external monitors. In my case, I have two regular DPI external monitors, and connect through a USB dock.
- Launch the Qt Nanobrowser example application.
- Put the laptop to sleep.
- Disconnect the laptop from the dock.
- Open and awaken the laptop.
The Nanobrowser application will crash. See attached backtrace.txt for backtrace – it appears the crash occurs while attempting to reset the top-level screen.