wxPython about event function

[RolleXu]

class container(wxPanel):
self.compnt is a control

the event func:

EVT_LEFT_DOWN(self,self.OnLeftDown)

when click container
self.OnLeftDown will be called
when click self.compnt
self.OnLeftDown won't be called

please tell me
why?
and how to call the func, both case?

thanks