Unexpectedly, I found myself needing to use IHTMLDocument5/6 last evening to fetch a few properties that aren’t directly exposed via any of the Web Browser options in classic .NET programming (like WinForms/WPF). I couldn’t find them anywhere, so I whipped up something simple/quick/dirty:

[Guid("3050f80c-98b5-11cf-bb82-00aa00bdce0b")]
[InterfaceTypeAttribute(ComInterfaceType.InterfaceIsDual)]
internal interface IHTMLDocument5
{
    void SetOnmousewheel(object p);
    object GetOnmousewheel();
    object docType { get; }
    object implementation { get; }
    object createAttribute([In] string attrName);
    object createComment([In] string comment);
    void SetOnfocusin(object p);
    object GetOnfocusin();
    void SetOnfocusout(object p);
    object GetOnfocusout();
    void SetOnactivate(object p);
    object GetOnactivate();
    void SetOndeactivate(object p);
    object GetOndeactivate();
    void SetOnbeforeactivate(object p);
    object GetOnbeforeactivate();
    void SetOnbeforedeactivate(object p);
    object GetOnbeforedeactivate();
    string compatMode { get; }
}


[Guid("30510417-98b5-11cf-bb82-00aa00bdce0b")]
[InterfaceTypeAttribute(ComInterfaceType.InterfaceIsDual)]
internal interface IHTMLDocument6
{
    object compatible { get; }
    object documentMode { get; }
    void SetOnStorage([In] object p);
    object GetOnStorage();
    void SetOnStorageCommit([In] object p);
    object GetOnStorageCommit();
    object getElementById([In] string id);
    void updateSettings();
}

As you can see, I didn’t spend a lot of time with the details, but it was enough to make progress (in particular I wanted compatMode and documentMode).