wxWindow over wxWindow invisible on Mac

[Enrico B.]

(wxwidgets 2.6.3 & 2.8.0 pc/mac )

Hi,

on mac platform when i create a wxGLCanvas on a wxWindow, the child 
wxGLCanvas is placed under the parent wxWindow (invisible ).
On msw no problem: child wxGLCanvas is placed over the parent wxWindow 
(visible )
I've seen the same problem in an older post (2005, without replies ) 
regarding wxWindow over wxWindow on mac.
Is this an old unresolved wxwidgets bug ? Can I set the window hierarchy 
? I tried Raise() without no effects. wxWindow is placed on a wxFrame.

Thanks,

Enrico Bedendo