C# Definition:

    [DllImport("user32")]
    public static extern bool ChangeWindowMessageFilterEx(IntPtr hWnd, uint msg, ChangeWindowMessageFilterExAction action,ref CHANGEFILTERSTRUCT changeInfo);

VB Definition:

Structure ChangeWindowMessageFilterEx
   Public TODO
End Structure

User-Defined Field Types:

    public enum MessageFilterInfo : uint
    {
        None=0, AlreadyAllowed=1, AlreadyDisAllowed=2, AllowedHigher=3
    };

    public enum ChangeWindowMessageFilterExAction : uint
    {
        Reset = 0, Allow = 1, DisAllow = 2
    };

    [StructLayout(LayoutKind.Sequential)]
    public struct CHANGEFILTERSTRUCT
    {
        public uint size;
        public MessageFilterInfo info;
    }

Notes: