Crash after QWidget::createWindowContainer(QWindow::fromWinId())

App is composed of two processes a Main and a Embedded. Main processes create the Embedded by using QProcess. The Main is attaching the Embedded window by using QWindow::fromWinId() and QWidget::createWindowContainer().

Testing:

1. Launch attached example EmbeddedWidgetCrash.zip
2. Wait for the window to open
3. Resize windows

Bug: If you resize the window, the application crashes

Windows 7, Qt5.12.2:

1. Launch attached example
2. Wait for the window to open
   
3. Resize windows. Crash:
   

Windows 7, Qt5.9.7:

1. Launch attached example
2. Wait for the window to open
     
3. Resize windows. Not crash: