title: Placing a Button in UltimateListCtrl using wxPython
body: <p>I'm new to Pythong and I have been trying to get a button within UltimateListCtrl. I still can't figure out what I'm doing wrong. Here is my code:</p>
  
  <pre><code>try:
      from agw import ultimatelistctrl as ULC
  except ImportError: # if it's not there locally, try the wxPython lib.
      from wx.lib.agw import ultimatelistctrl as ULC 
  
  
  self.table = ULC.UltimateListCtrl(self, -1, agwStyle=ULC.ULC_REPORT|
                                              ULC.ULC_HAS_VARIABLE_ROW_HEIGHT)
  
  self.table.InsertColumn(0, "Name")
  self.table.InsertColumn(1, "Size")
  self.table.InsertColumn(2, "Download")
  
  
  for i in range(0, len(masterlist)):
      pos = self.table.InsertStringItem(i,str(masterlist[i]['name']))
      self.table.SetStringItem(pos, 1,str(masterlist[i]['size']))
      button = wx.Button(self, id=i, label="Download")
      self.table.SetItemWindow(pos, col=2, wnd=button, expand=True)
  </code></pre>
  
  <p>masterlist is a list of download items.</p>
  
  <p>I get this traceback:</p>
  
  <pre><code>Traceback (most recent call last):
  File "E:\TestApp.py", line 67, in Display
  self.table.SetItemWindow(pos, col=5, wnd=button, expand=True)
  File "C:\Python27\lib\site-packages\wx-2.8-msw-unicode\wx\lib\agw\ultimatelistctrl.py", line 12961, in SetItemWindow
  return self._mainWin.SetItemWindow(item, wnd, expand)
  File "C:\Python27\lib\site-packages\wx-2.8-msw-unicode\wx\lib\agw\ultimatelistctrl.py", line 9021, in SetItemWindow
  item.SetWindow(wnd, expand)
  File "C:\Python27\lib\site-packages\wx-2.8-msw-unicode\wx\lib\agw\ultimatelistctrl.py", line 1863, in SetWindow
  mainWin = listCtrl._mainWin
  AttributeError: 'MainWindow' object has no attribute '_mainWin'
  </code></pre>