[wxPython] popup a pull down menu

I try to create a pulldown menu, for right cilck event in TreeCtrl.
See the below lines of code. I've created the menu, but menu.Show(TRUE) is
throughing invalid Attribute error.

1) How can one popup created menu at event.GetPosition() point?

    self.PopupMenu(menu, pos)

Robin, In solaris, still the menu is poped up. why? In w2k working
excellent.