[MarshalAs(UnmanagedType.LPArray)] ThumbButton[] pButtons);

     [MarshalAs(UnmanagedType.LPArray)] ThumbButton[] pButtons);

    Function ThumbBarAddButtons(hwnd As IntPtr, cButtons As UInteger, <MarshalAs(UnmanagedType.LPArray)> pButtons As ThumbButton()) As HResult

    Function ThumbBarUpdateButtons(hwnd As IntPtr, cButtons As UInteger, <MarshalAs(UnmanagedType.LPArray)> pButtons As ThumbButton()) As HResult

    /// <param name="pButton">A pointer to an array of THUMBBUTTON structures. Each THUMBBUTTON defines an

    [MarshalAs(UnmanagedType.LPArray)] THUMBBUTTON[] pButton);

    [MarshalAs(UnmanagedType.LPArray)] THUMBBUTTON[] pButton);

THUMBBUTTON

enum THUMBBUTTONMASK{

struct THUMBBUTTON{

    THUMBBUTTONMASK   dwMask;

    THUMBBUTTONFLAGS  dwFlags;

enum THUMBBUTTONFLAGS{

     [MarshalAs(UnmanagedType.LPArray)] ThumbButton[] pButtons);

     [MarshalAs(UnmanagedType.LPArray)] ThumbButton[] pButtons);

public struct THUMBBUTTON

    public THUMBBUTTONMASK dwMask;

    public THUMBBUTTONFLAGS dwFlags;

Structure THUMBBUTTON