def _plug_area_center(area, widget, frame, guide):
    if widget is not None:
        return False
    if isinstance(frame, QDockWindow):
        temp_area = frame.dockArea()
        frame.setDockArea(None)
        _merge_dock_bars(area, temp_area)
        area.setCentralWidget(temp_area.centralWidget())
    else:
        if frame.isWindow():
            frame.unfloat()
        area.setCentralWidget(frame)
    return True
Plug the frame as the area center.
dataset/ETHPy150Open nucleic/enaml/enaml/qt/docking/layout_handling.py/_plug_area_center