title: This program using wxpython don't run
body: <p>This program is that wx.textctrl is written "clicked" when button is clicked.</p>
  
  <p>It don't run.</p>
  
  <pre><code>import wx
  
  class Mainwindow(wx.Frame):
  
      def __init__(self, parent, id, title):
          wx.Frame.__init__(self, parent, id, title, size=(300, 300))
          panel = wx.Panel(self, -1)
  
          vbox = wx.BoxSizer(wx.VERTICAL)
  
          hbox1 = wx.BoxSizer(wx.HORIZONTAL)
          btn = wx.Button(panel, -1, 'OK', size=(70, 30))
          button = Click_btn()
          btn.Bind(wx.EVT_BUTTON, button.click_btn)
          hbox1.Add(btn, 0)
          vbox.Add(hbox1, 0)
  
          hbox2 = wx.BoxSizer(wx.HORIZONTAL) 
          self.tc = wx.TextCtrl(panel, -1, style=wx.TE_MULTILINE)
          hbox2.Add(self.tc, 1, wx.EXPAND) 
          vbox.Add(hbox2, 1, wx.EXPAND)
  
          panel.SetSizer(vbox)
  
          self.Centre()
          self.Show(True)
  
  class Click_btn(Mainwindow):
      def click_btn(self, event):
          Mainwindow.tc.WriteText("clicked\n")
  
  if __name__=="__main__":
      app = wx.App()
      Mainwindow(None, -1, u"sample")
      app.MainLoop()
  </code></pre>
  
  <p>Error panel disapper immediately.</p>
  
  <p>Maybe Click_btn class is wrong.</p>
  
  <p>Where should I change?</p>