HTML - How do I know when all frames are loaded?

I'm using .NET WebBrowser control. How do I know when a web page is fully loaded?

I want to know when the browser is not fetching any more data. (The moment when IE writes 'Done' in its status bar...).

Notes:

The DocumentComplete/NavigateComplete events might occur multiple times for a web site containing multiple frames.
The browser ready state doesn't solve the problem either.
I have tried checking the number of frames in the frame collection and then count the number of times I get DocumentComplete event but this doesn't work either.
this.WebBrowser.IsBusy doesn't work either. It is always 'false' when checking it in the Document Complete handler.

Solution

Here's what finally worked for me:

       public bool WebPageLoaded
    {
        get
        {
            if (this.WebBrowser.ReadyState != System.Windows.Forms.WebBrowserReadyState.Complete)
                return false;

            if (this.HtmlDomDocument == null)
                return false;

            // iterate over all the Html elements. Find all frame elements and check their ready state
            foreach (IHTMLDOMNode node in this.HtmlDomDocument.all)
            {
                IHTMLFrameBase2 frame = node as IHTMLFrameBase2;
                if (frame != null)
                {
                    if (!frame.readyState.Equals("complete", StringComparison.OrdinalIgnoreCase))
                        return false;

                }
            }

            Debug.Print(this.Name + " - I think it's loaded");
            return true;
        }
    }

On each document complete event I run over all the html element and check all frames available (I know it can be optimized). For each frame I check its ready state. It's pretty reliable but just like jeffamaphone said I have already seen sites that triggered some internal refreshes. But the above code satisfies my needs.

Edit: every frame can contain frames within it so I think this code should be updated to recursively check the state of every frame.