Python-сообщество

from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys, os
from mainwindow_ui import *
class mainwindow(QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        QMainWindow.__init__(self)
        
        
        self.setupUi(self)
        
        self.connect(self.leftListWidget,  QtCore.SIGNAL('doubleClicked(QModelIndex)'),  self, QtCore.SLOT('itemClicked(item)'))
        
        self.connect(self.exitButton, QtCore.SIGNAL('clicked()'), self.exitAction)
        self.updateLeftList(os.path.expanduser("~"))
        self.updateRightList(os.path.expanduser("~"))
    def updateLeftList(self, directory):
        files = os.listdir(directory)
        for f in files:
            self.leftListWidget.addItem(f)
    
    def updateRightList(self, directory):
        files = os.listdir(directory)
        for f in files:
            self.rightListWidget.addItem(f)
    
    def itemClicked(self,  item):
        messageBox = QMessageBox(self)
        messageBox.setText("Hello")
        messageBox.show()
    
    def exitAction(self):
        self.close()

self.leftListWidget.doubleClicked.connect(self.itemClicked)