class Frm(wx.Frame):

    def __init__(self, *args, **kwargs):
        super(Frm, self).__init__(*args, **kwargs)
txt = wx.TextCtrl(self)
s = wx.BoxSizer(wx.HORIZONTAL)
s.Add(txt, 1)
self.SetSizer(s)
self.Layout()
app = wx.PySimpleApp()
frame = Frm(None)
frame.Show()
app.MainLoop()
How do I modify the width of a TextCtrl in wxPython?