C# Definition:

public enum ExtStatusEnum : uint
{
    MSGFLTINFO_NONE = 0,
    /// <summary>
    /// The message is allowed at a scope higher than the window
    /// </summary>
    MSGFLTINFO_ALREADYALLOWED_FORWND,
    /// <summary>
    /// The message has already been allowed by this window's message filter,
    /// and the function thus succeeded with no change to the window's message filter
    /// </summary>
    MSGFLTINFO_ALREADYDISALLOWED_FORWND,
    /// <summary>
    /// The message is allowed at a scope higher than the window
    /// </summary>
    MSGFLTINFO_ALLOWED_HIGHER
}

VB Definition:

Enum ExtStatusEnum
   TODO
End Enum

Notes:

This isn't an official enum name, these values were put together from #Defines in the header file