how to open a Dialog window on top of my mainwindow

[implor]

When I try go show a window (AddUserGui) it just resize the Ui_MainWindow. I think the problem occurs when I send "self" as a argument. How do you solve this? or is this a stuipd way to do it?



from PyQt4 import QtCore, QtGui
from libarylib import *
from bibgui import Ui_MainWindow
from addusergui import Ui_Dialog as AddUserGui
import sys


class mainGuiWindow(QtGui.QMainWindow):

def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)

self.connect(self.ui.pushButton_3, QtCore.SIGNAL("clicked()"), self.addUser)



def addUser(self):
self.adduser = AddUserGui()
self.adduser.setupUi(self) #<-- this don't work








if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
myapp = mainGuiWindow()
myapp.show()
sys.exit(app.exec_())