Focus managing in the chrome

Hi

I developp a browser with gecko 1.9.2.25. (Visual 2008).

In my chrome I cannot manage the focus

I tried to do

nsCOMPtr<nsIWebBrowserFocus> focus(do_GetInterface(myWebBrowserChrome-
>mWebBrowser));

but when I do a focus->Activate() I get an C00005 error (on windows).

It would be good if someone could explain me how to manage the focus
with this gecko's version. Ans how to use in my chrome (My chrome is
public nsIWebBrowserChromeFocus and  use the declaration
NS_DECL_NSIWEBBROWSERCHROMEFOCUS and
NS_INTERFACE_MAP_ENTRY(nsIWebBrowserChromeFocus)).


- setFocus,  (returns only NS_OK)
- FocusNextElement (returns NS_ERROR_NOT_IMPLEMENTED)
- FocusPrevElement (returns NS_ERROR_NOT_IMPLEMENTED).


If someone has sample of how to use it with such a version

Thank's for your help

philippe