This happens most easily in debug mode, though you can see some hints that it's not quite behaving right in release. I think the responsiveness of the render loop may have something to do with whether it spirals out of control or not.
Below are the errors generated when this happens. Notice how near the bottom the geometry
values seem to be in a feedback loop, getting bigger in magnitude and jumping from positive to negative.
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=826,2411 1300x768) with invalid geometry: QRect(826,2411 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=381,-996 1300x768) with invalid geometry: QRect(381,-996 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=1305,5204 1300x768) with invalid geometry: QRect(1305,5204 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=166,1983 1300x768) with invalid geometry: QRect(166,1983 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=187,1971 1300x768) with invalid geometry: QRect(187,1971 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=654,1978 1300x768) with invalid geometry: QRect(654,1978 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=654,1975 1300x768) with invalid geometry: QRect(654,1975 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=654,1967 1300x768) with invalid geometry: QRect(654,1967 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=656,1962 1300x768) with invalid geometry: QRect(656,1962 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=619,1984 1300x768) with invalid geometry: QRect(619,1984 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=528,1975 1300x768) with invalid geometry: QRect(528,1975 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=932,1964 1300x768) with invalid geometry: QRect(932,1964 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-985,1979 1300x768) with invalid geometry: QRect(-985,1979 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-1016,1965 1300x768) with invalid geometry: QRect(-1016,1965 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-937,1978 1300x768) with invalid geometry: QRect(-937,1978 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-401,1980 1300x768) with invalid geometry: QRect(-401,1980 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-1149,1977 1300x768) with invalid geometry: QRect(-1149,1977 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-1291,1978 1300x768) with invalid geometry: QRect(-1291,1978 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-1291,1963 1300x768) with invalid geometry: QRect(-1291,1963 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-1278,1981 1300x768) with invalid geometry: QRect(-1278,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-1262,1981 1300x768) with invalid geometry: QRect(-1262,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-1232,1981 1300x768) with invalid geometry: QRect(-1232,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-1009,1981 1300x768) with invalid geometry: QRect(-1009,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-958,1981 1300x768) with invalid geometry: QRect(-958,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-865,1978 1300x768) with invalid geometry: QRect(-865,1978 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-149,1971 1300x768) with invalid geometry: QRect(-149,1971 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-149,1971 1300x768) with invalid geometry: QRect(-149,1971 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=71,1991 1300x768) with invalid geometry: QRect(71,1991 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=14,1981 1300x768) with invalid geometry: QRect(14,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=14,1980 1300x768) with invalid geometry: QRect(14,1980 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=10,1976 1300x768) with invalid geometry: QRect(10,1976 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-39,1967 1300x768) with invalid geometry: QRect(-39,1967 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-39,1966 1300x768) with invalid geometry: QRect(-39,1966 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-38,1981 1300x768) with invalid geometry: QRect(-38,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-31,1981 1300x768) with invalid geometry: QRect(-31,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-8,1981 1300x768) with invalid geometry: QRect(-8,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=5,1981 1300x768) with invalid geometry: QRect(5,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=15,1981 1300x768) with invalid geometry: QRect(15,1981 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-550,1977 1300x768) with invalid geometry: QRect(-550,1977 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-593,1974 1300x768) with invalid geometry: QRect(-593,1974 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=637,1980 1300x768) with invalid geometry: QRect(637,1980 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=633,1978 1300x768) with invalid geometry: QRect(633,1978 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=2462,2294 1300x768) with invalid geometry: QRect(2462,2294 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=2462,2294 1300x768) with invalid geometry: QRect(2462,2294 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-6437,-3968 1300x768) with invalid geometry: QRect(-6437,-3968 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=26906,20174 1300x768) with invalid geometry: QRect(26906,20174 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)
QSGThreadedRenderLoop: expose event received for window QQuickWindowQmlImpl_QML_135(0x4eca9c70 active exposed, visibility=QWindow::Windowed, flags=QFlags<Qt::WindowType>(Window|FramelessWindowHint), geometry=-25760,-19844 1300x768) with invalid geometry: QRect(-25760,-19844 1300x768) on QScreen(0x1fc2e0, name=\\.\DISPLAY1)