Incorrect modal dialog 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(). Main widget and Embedded widget have buttons for creation QDialog and QFileDialog.

Button "Main widget modal dialog" works correctly
Button "Main widget file dialog" works correctly
Button "Embeded widget modal dialog" don't works correctly
Button"Embeded widget file dialog" works correctly

Test case for embeded widget modal QDialog:

1. Launch attached example ModalDialog.zip
2. Click button "Embeded widget modal dialog".
   Embeded widget modal dialog will open
   
3. Click main widget heder. Main widget is available
   
   But the main widget must be unavailable.
4. Drag main widget
   
   But the main widget must be unavailable.
5. Click button "Main widget file dialog"
   
   But the main widget must be unavailable.

Note:  QFileDialog ( Click button"Embeded widget file dialog") do main widget is unavailable

Request: for modal QDialog ensure behavior similar modal QFileDialog