[REG 5.3.2->5.4] Windows: opengl assert when closing QML main window when QML windows are aggregated in a QtObject

Steps:

• Compile the attached project.
• Run the executable and close the window
• Assert appears with

  ASSERT: "context" in file opengl\qopenglfunctions.cpp, line 209
  Invalid parameter passed to C runtime function.
  Invalid parameter passed to C runtime function.
  

I have attached the backtrace and opengl extensions.

Notes:

• It does not happen with Qt 5.3.2.
• The bug disappears when removing in MainWindow.qml the code

  ConfigurationTab {}
  

• The bug disappears when removing in main.qml the code

      property var splash: Window {
          visible: false
          modality: Qt.ApplicationModal
          flags: Qt.SplashScreen
          width: 300
          height: 200
          color: "grey"
      }
  

• the bug disappears when changing QApplication for QGuiApplication

QML code looks like:

....
QtObject {
    id : mainQtObject
    property var window: MainWindow {
        visible: true
    }
    property var splash: Window {
        visible: false
...
    }
}