Parent Qt to non-qt window with PyQt

Question

I am trying to parent a QMainWindow to a non-qt application (the application may change). Any ideas on how to do this?

The qt window opens fine and i can interact with the python API in the applications however the qt window goes behind the application window if i click on the application. I could use Qt.WindowStaysOnTopHint flag but then it's on top of everything which isn't ideal.

Psuedo Example: If you were using an application (example Nuke) where the main application is also qt based you would use something like:

def _nuke_main_window():
    """Returns Nuke's main window"""
    for obj in QtWidgets.qApp.topLevelWidgets():
        if (obj.inherits('QMainWindow') and
                obj.metaObject().className() == 'Foundry::UI::DockMainWindow'):
            return obj
    else:
        raise RuntimeError('Could not find DockMainWindow instance')

wdg = myWidget(parent=_nuke_main_window())
wdg.show()

Maya and any other pyqt based window also would work similarly.

However if the application isnt qt based:

wdg = myWidget(parent=nonQtWindowQt_ised)
wdg.show()

where:

def nonQtWindowQt_ised():
    #return the application main window somehow maybe through python bindings like SIP?

Any examples (ideally) or useful direction would be much appreciated.

Using PyQt5, Python 3.5 and Linux.