Cannot turn off combo box text events in OS X

All:

When I run this script, the choice control does not respond visually to button clicks, which is what I want, but the combo box does. You can select items on the combo box, while the choice is completely inert. Is there another event I need to capture or turn off for the combo box in order to make it inert?

Craig

from wxPython.wx import *
class panel(wxPanel):
     def __init__(self, parent):
         wxPanel.__init__(self, parent, -1)
         ItemList = 'item1', 'item2', 'item3'
         b1 = wxComboBox(self, 20, ItemList[1], (10, 10), (90, 40), ItemList, wxCB_SIMPLE)
         b2 = wxChoice(self, 20, (10, 110), (90, 40), ItemList)
         self.Disconnect(-1, -1, wxEVT_COMMAND_COMBOBOX_SELECTED)
         self.Disconnect(-1, -1, wxEVT_COMMAND_CHOICE_SELECTED)
         self.Disconnect(-1, -1, wxEVT_COMMAND_TEXT_UPDATED)
         self.Disconnect(-1, -1, wxEVT_COMMAND_TEXT_ENTER)
         b1.Connect(-1, -1, wxEVT_LEFT_DOWN, self.OnRunEvent)
         b2.Connect(-1, -1, wxEVT_LEFT_DOWN, self.OnRunEvent)
         b1.Connect(-1, -1, wxEVT_LEFT_DCLICK, self.OnRunEvent)
         b2.Connect(-1, -1, wxEVT_LEFT_DCLICK, self.OnRunEvent)

     def OnRunEvent(self, event):
         type = event.GetEventType()
         if type == wxEVT_COMMAND_COMBOBOX_SELECTED:
             print 'wxEVT_COMMAND_COMBOBOX_SELECTED'
         elif type == wxEVT_COMMAND_CHOICE_SELECTED:
             print 'wxEVT_COMMAND_CHOICE_SELECTED'
         elif type == wxEVT_COMMAND_TEXT_UPDATED:
             print 'wxEVT_COMMAND_TEXT_UPDATED'
         elif type == wxEVT_COMMAND_TEXT_ENTER:
             print 'wxEVT_COMMAND_TEXT_ENTER'
         elif type == wxEVT_LEFT_DOWN:
             print 'wxEVT_LEFT_DOWN'
         elif type == wxEVT_LEFT_DCLICK:
             print 'wxEVT_LEFT_DCLICK'
         else:
             print 'cannot find event type'

app = wxPySimpleApp()
f = wxFrame(None, -1,'ComboBox Test', (200, 200), (350, 200))
p = panel(f)
f.Show()
app.MainLoop()