Since Qt 5.12, showing a modal QDialog over a QML window may freeze the dialog. The issue only seems to appear on macOS, when the default QSurfaceFormat has swapBehavior set to SingleBuffer.
Minimal reproduction project attached:
- Launch project
- See a small modal QDialog on top of a QML window
- Clicking the checkbox in the QDialog does not change its visual state
- Clicking the checkbox updates its visual state (checked/unchecked)
This worked as expected on macOS+Qt 5.11.2, and works as expected on win/linux+Qt5.12/5.13