from wxPython.wx import *

class MainFrame(wxMDIParentFrame):
    def __init__(self, parent):
        wxMDIParentFrame.__init__(self, id = -1, parent = parent, title = 
'Test',
                        style = wxDEFAULT_FRAME_STYLE | wxVSCROLL | 
wxHSCROLL)

        self.MenuBar = wxMenuBar()
        self.Menu = wxMenu()
        self.Menu.Append(id = 10, item = 'New that works...')
        self.Menu.Append(id = 11, item = 'New that dont work...')
        EVT_MENU(self, 10, self.OnWorksMenu)
        EVT_MENU(self, 11, self.OnDontWorkMenu)
        self.MenuBar.Append(menu = self.Menu, title = 'Child')

        self.SetClientSize(wxSize(475, 311))
        self.SetMenuBar(self.MenuBar)
        self.SetAutoLayout(true)

    def OnWorksMenu(self, event):
        import Child
        Child.ChildFrame(self, 1).Show(true)

    def OnDontWorkMenu(self, event):
        import Child
        Child.ChildFrame(self, 0).Show(true)

app = wxPySimpleApp()
frame = MainFrame(None)
frame.Show(true)
app.MainLoop()