[StructLayout(LayoutKind.Sequential, Pack = 8, CharSet = CharSet.Unicode)]
public struct THUMBBUTTON
{
public THUMBBUTTONMASK dwMask;
public uint iId;
public uint iBitmap;
public IntPtr hIcon;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 259)]
public string szTip;
public THUMBBUTTONFLAGS dwFlags;
}