[PyQt] Painting an arc... can't be that hard?

[Scott Price]

So, using PyQt4/WindowsXP:  

I'm attempting to adapt the basic drawing example for the simple purpose of
drawing an arc on the background of a widget.  The following code opens a
main window with a child widget inside, but doesn't draw the arc.  Probably
something simple that I'm missing, but I can't spot it... My eyes are
crossing from reading the documentation and attempting different things.

What have I missed? 

import sys
from PyQt4 import QtGui, QtCore
    
class GroupDialog(QtGui.QWidget):
    def __init__(self):
        QtGui.QWidget.__init__(self)
               
        self.setBackgroundRole(QtGui.QPalette.Base)
        self.drawMe()
        
    def drawMe(self):

        self.update()
        
    def paintEvent(self, event):
    
        rect = QtCore.QRect(10, 20, 80, 60)

        self.pen = QtGui.QPen(QtCore.Qt.blue)
        self.pen.setWidth(2)
        self.pen.setCapStyle(QtCore.Qt.RoundCap)
        self.pen.setStyle(QtCore.Qt.SolidLine)

        startAngle = 30 * 16
        arcLength = 120 * 16
        
        painter = QtGui.QPainter()
        painter.begin(self)
        painter.setPen(self.pen)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)

        painter.drawArc(rect, startAngle, arcLength)
        
        painter.end()
        
class MyWindow(QtGui.QMainWindow):
    def __init__(self):
        QtGui.QMainWindow.__init__(self)

        groupDialog = GroupDialog()
        self.scrollArea = QtGui.QScrollArea()
        self.scrollArea.setWidget(groupDialog)
        self.setCentralWidget(self.scrollArea)
            
if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    mainwindow = MyWindow()
    mainwindow.setGeometry(0,25,800,525)
    mainwindow.show()
    sys.exit(app.exec_())  

Thanks!
Scott