Mixing PyQt4 and Maya UI objects

modelPanelPyQt4.py

from PyQt4 import QtCore, QtGui

import maya.cmds as cmds
import maya.OpenMayaUI as mui

import sip

global app


class MyDialog(QtGui.QDialog):

    def __init__(self, parent=None):
        super(MyDialog, self).__init__(parent=parent)
        
        self.setObjectName("MyWindow")
        self.resize(800, 600)
        self.setWindowTitle("PyQt ModelPanel Test")

        self.verticalLayout = QtGui.QVBoxLayout(self)
        self.verticalLayout.setObjectName("mainLayout")
        layout = mui.MQtUtil.fullName(long(sip.unwrapinstance(self.verticalLayout)))
        cmds.setParent(layout)

        self._cameraName = cmds.camera()[0]
        nodeName = cmds.modelPanel(cam=self._cameraName)
        ptr = mui.MQtUtil.findControl(nodeName)
        self.modelPanel = sip.wrapinstance(long(ptr), QtCore.QObject)

        self.verticalLayout.addWidget(self.modelPanel)

    def show(self):
        super(MyDialog, self).show()
        self.modelPanel.repaint()
                    

def show():
    global app
    app = QtGui.QApplication.instance()

    ptr = mui.MQtUtil.mainWindow()
    win = sip.wrapinstance(long(ptr), QtCore.QObject)
    d = MyDialog(parent=win)
    d.show()

    return d