Hi,
The IHTMLFrameBase doesn't give acess to the Document, how did you managed to get it from there ???

If you want to get the document from a frame, the
get_document of the IHTMLWindow2 seems to work fine.

So you only need to query each Frame Item for a IHTMLWindow2 and then use the get_document if
the returned IHTMLDocument2 isn't null then you are probably dealing with a frame.
Once you have the frame you can Query it for a
IOleWindow and then get the window Handle.

If you managed to get the document of a IFRAME from another Frame, please let me know.

thanks,