C# Definition:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct STARTUPINFOEX
{
     public STARTUPINFO StartupInfo;
     public IntPtr lpAttributeList;
}

VB Definition:

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Unicode)>
Public Structure STARTUPINFOEX
   Public StartupInfo As STARTUPINFO
   Public lpAttributeList As IntPtr
End Structure

User-Defined Field Types:

None.

Notes:

See CreateProcess and InitializeProcThreadAttributeList,UpdateProcThreadAttribute

Do not forget to set the size of your object after filling in the attributes, before calling CreateProcess

        startupInfoEx.StartupInfo.cb = Marshal.SizeOf(startupInfoEx);