[StructLayout(LayoutKind.Sequential)]
public struct COMPPOS
{
     public const int COMPONENT_TOP = 0x3FFFFFFF;
     public const int COMPONENT_DEFAULT_LEFT = 0xFFFF;
     public const int COMPONENT_DEFAULT_TOP = 0xFFFF;
     public static readonly int SizeOf = Marshal.SizeOf(typeof(COMPPOS));

     public int dwSize;
     public int iLeft;
     public int iTop;
     public int dwWidth;
     public int dwHeight;
     public int izIndex;
     [MarshalAs(UnmanagedType.Bool)]
     public bool fCanResize;
     [MarshalAs(UnmanagedType.Bool)]
     public bool fCanResizeX;
     [MarshalAs(UnmanagedType.Bool)]
     public bool fCanResizeY;
     public int iPreferredLeftPercent;
     public int iPreferredTopPercent;
}

VB Definition:

<StructLayout(LayoutKind.Sequential)> _
Public Structure COMPPOS
    Public Const COMPONENT_TOP As Integer = &H3FFFFFFF
    Public Const COMPONENT_DEFAULT_LEFT As Integer = &HFFFF
    Public Const COMPONENT_DEFAULT_TOP As Integer = &HFFFF
    Public Shared ReadOnly SizeOf As Integer
    Public dwSize As Integer
    Public iLeft As Integer
    Public iTop As Integer
    Public dwWidth As Integer
    Public dwHeight As Integer
    Public izIndex As Integer
    <MarshalAs(UnmanagedType.Bool)> _
    Public fCanResize As Boolean
    <MarshalAs(UnmanagedType.Bool)> _
    Public fCanResizeX As Boolean
    <MarshalAs(UnmanagedType.Bool)> _
    Public fCanResizeY As Boolean
    Public iPreferredLeftPercent As Integer
    Public iPreferredTopPercent As Integer
    Shared Sub New()
    COMPPOS.SizeOf = Marshal.SizeOf(GetType(COMPPOS))
    End Sub
End Structure