Simple decimal RGB to hex converter on wxPython [Fixed]

import wx
import wx.xrc


###########################################################################
## Class MyFrame1
###########################################################################

class MyFrame1(wx.Frame):

    def __init__(self, parent):
        wx.Frame.__init__(self, parent, id=wx.ID_ANY, title=wx.EmptyString,
                          pos=wx.DefaultPosition, size=wx.Size(180, 180),
                          style=wx.DEFAULT_FRAME_STYLE | wx.STAY_ON_TOP |
                          wx.TAB_TRAVERSAL)

        self.SetSizeHints(wx.DefaultSize, wx.DefaultSize)

        bSizer1 = wx.BoxSizer(wx.VERTICAL)

        self.m_textCtrl1 = wx.TextCtrl(self, wx.ID_ANY, wx.EmptyString,
                                       wx.DefaultPosition, wx.DefaultSize, 0)
        bSizer1.Add(self.m_textCtrl1, 0, wx.ALL, 5)

        self.m_textCtrl2 = wx.TextCtrl(self, wx.ID_ANY, wx.EmptyString,
                                       wx.DefaultPosition, wx.DefaultSize, 0)
        bSizer1.Add(self.m_textCtrl2, 0, wx.ALL, 5)

        self.m_textCtrl3 = wx.TextCtrl(self, wx.ID_ANY, wx.EmptyString,
                                       wx.DefaultPosition, wx.DefaultSize, 0)
        bSizer1.Add(self.m_textCtrl3, 0, wx.ALL, 5)

        self.m_textCtrl4 = wx.TextCtrl(self, wx.ID_ANY, "000000",
                                       wx.DefaultPosition, wx.DefaultSize,
                                       wx.TE_READONLY)
        bSizer1.Add(self.m_textCtrl4, 0, wx.ALL, 5)

        self.SetSizer(bSizer1)
        self.Layout()

        self.Centre(wx.BOTH)

        # Connect Events
        self.m_textCtrl1.Bind(wx.EVT_TEXT, self.on_change)
        self.m_textCtrl2.Bind(wx.EVT_TEXT, self.on_change)
        self.m_textCtrl3.Bind(wx.EVT_TEXT, self.on_change)


    def on_change(self, event):
        def convert(s):
            try:
                n = int(s)
            except ValueError:
                n = 0
            if n > 255:
                n = 255
            return n

        r = convert(self.m_textCtrl1.GetValue())
        g = convert(self.m_textCtrl2.GetValue())
        b = convert(self.m_textCtrl3.GetValue())

        self.m_textCtrl4.SetValue("%02X%02X%02X" % (r, g, b))


###########################################################################
## __main__
###########################################################################

if __name__ == '__main__':
    app = wx.App(False)
    frame = MyFrame1(None)
    frame.Show(True)
    app.MainLoop()