C# Definition:

    [StructLayout(LayoutKind.Sequential)]
    public struct WINDOWPOS
    {
        public IntPtr hwnd;
        public IntPtr hwndInsertAfter;
        public int x;
        public int y;
        public int cx;
        public int cy;
        public uint flags;
    }

VB Definition:

    <StructLayout(LayoutKind.Sequential)> _
    Public Structure WINDOWPOS
        Public hwnd As IntPtr
        Public hwndInsertAfter As IntPtr
        Public x As Integer
        Public y As Integer
        Public cx As Integer
        Public cy As Integer
        Public flags As Integer
    End Structure

User-Defined Field Types:

None.

On MSDN order of hwnd and hwndInsertAfter is wrong. Here it corresponds with winuser.h from sdk...

Notes:

None.