spontaneous segv crashes on macOS

since the update to 4.14.2 I experience frequent segv crashes, typically when using Qt Creator again after it has been iconfied for a longer time, such as overnight. From the attached crash report, it appears that to happen in QScreen::availableGeometry() while it tries to show a tooltip. I suspect it's trying to use a cached QScreen handle that is no longer valid - the external monitor I typically use for code dev is usually unplugged overnight.