LinuxQuestions.org - Python/PyQt4 - Newbie Structure question

Ok i've been playing with PyQt4
i have made the following app that works fine:

Code:

#!/usr/bin/env python 



import sys

import time

from PyQt4 import QtGui, QtCore



class MainWindow(QtGui.QWidget):

    def __init__(self):

        self.buildWindow()

        

    def buildWindow(self, parent=None):

            QtGui.QWidget.__init__(self, parent)

        self.setGeometry(150, 100, 800, 600)

        self.setWindowTitle('::System Log::')

        quitBtn = QtGui.QPushButton('close', self)

        quitBtn.setGeometry(720, 550, 60, 40)

        self.connect(quitBtn, QtCore.SIGNAL('clicked()'),

            QtGui.qApp, QtCore.SLOT('quit()'))

        self.logwidget = QtGui.QTextEdit('', self)

        self.logwidget.setGeometry(5, 5, 790, 540)

        self.logwidget.isReadOnly()

        self.logwidget.setFontPointSize(7)

        self.logwidget.append('Welcome Jerks!')



    def LogParse(self):

        logfile = open('/var/log/syslog', 'r')

        self.logwidget.clear()

        for line in logfile:

            self.logwidget.append(line)

        logfile.close()



app = QtGui.QApplication(sys.argv)

mainwindow = MainWindow()

mainwindow.show()

mainwindow.LogParse()

sys.exit(app.exec_())

However im confused about how it is exectued. I would like see the main window and then run 'LogParse()' to fill the QTextEdit widget. As is the main window doesn't appear until after 'LogParse' runs. Ultimately i want 'LogParse' inside a 'while' loop with a sleep() to update the contents of the QTextEdit widget every few seconds.
I've missed something fundamental here and cant seem to rearange things to work this way.
Can someone show me what that might look like?
Thanks in advance