#!/usr/bin/env python
# -*- coding: utf-8 -*-
from PyQt4 import QtCore, QtGui
import sys
class Main_Frame(QtGui.QFrame):
    def __init__(self, parent = None):
        QtGui.QFrame.__init__(self, parent)
        self.label = QtGui.QLabel("Hello")
        hbox = QtGui.QHBoxLayout()
        hbox.addWidget(self.label)
        self.setLayout(hbox)
class MyWindow(QtGui.QMainWindow):
    def __init__(self, parent = None):
        QtGui.QMainWindow.__init__(self, parent)
        self.setWindowFlags(QtCore.Qt.Window |
                            QtCore.Qt.WindowSystemMenuHint)
        self.resize(800, 600)
        self.main_frame = Main_Frame()
        self.layout().addWidget(self.main_frame)
app = QtGui.QApplication(sys.argv)
window = MyWindow()
window.show()
sys.exit(app.exec_())

class MyWindow(QtGui.QMainWindow):
    def __init__(self, parent = None):
        QtGui.QMainWindow.__init__(self, parent)
        self.setWindowFlags(QtCore.Qt.Window |
                            QtCore.Qt.WindowSystemMenuHint)
        self.main_frame = Main_Frame()
        self.setCentralWidget(self.main_frame)