I have declared the PrinterNotifyInfo structure that it wants in as a class thus:

Imports System.Runtime.InteropServices <StructLayout(LayoutKind.Explicit)> _ Public Class PrinterNotifyOptions     <FieldOffset(0)> Public dwVersion As Integer     <FieldOffset(4)> Public dwFlags As Integer     <FieldOffset(8)> Public Count As Integer     '\ --JOB_NOTIFY_OPTIONS_TYPE     <FieldOffset(12)> Public wType As Int16     <FieldOffset(14)> Public wReserved0 As Int16     <FieldOffset(16)> Public dwReserved1 As Int32     <FieldOffset(20)> Public dwReserved2 As Int32     <FieldOffset(24)> Public FieldCount As Int32     <FieldOffset(28)> Public pFields As IntPtr #Region "Public Enumerated Types"     Public Enum Printer_Notification_Types         PRINTER_NOTIFY_TYPE = &H0         JOB_NOTIFY_TYPE = &H1     End Enum     Public Enum Printer_Notify_Field_Indexes         PRINTER_NOTIFY_FIELD_SERVER_NAME = &H0         PRINTER_NOTIFY_FIELD_PRINTER_NAME = &H1         PRINTER_NOTIFY_FIELD_SHARE_NAME = &H2         PRINTER_NOTIFY_FIELD_PORT_NAME = &H3         PRINTER_NOTIFY_FIELD_DRIVER_NAME = &H4         PRINTER_NOTIFY_FIELD_COMMENT = &H5         PRINTER_NOTIFY_FIELD_LOCATION = &H6         PRINTER_NOTIFY_FIELD_DEVMODE = &H7         PRINTER_NOTIFY_FIELD_SEPFILE = &H8         PRINTER_NOTIFY_FIELD_PRINT_PROCESSOR = &H9         PRINTER_NOTIFY_FIELD_PARAMETERS = &HA         PRINTER_NOTIFY_FIELD_DATATYPE = &HB         PRINTER_NOTIFY_FIELD_SECURITY_DESCRIPTOR = &HC         PRINTER_NOTIFY_FIELD_ATTRIBUTES = &HD         PRINTER_NOTIFY_FIELD_PRIORITY = &HE         PRINTER_NOTIFY_FIELD_DEFAULT_PRIORITY = &HF         PRINTER_NOTIFY_FIELD_START_TIME = &H10         PRINTER_NOTIFY_FIELD_UNTIL_TIME = &H11         PRINTER_NOTIFY_FIELD_STATUS = &H12         PRINTER_NOTIFY_FIELD_STATUS_STRING = &H13         PRINTER_NOTIFY_FIELD_CJOBS = &H14         PRINTER_NOTIFY_FIELD_AVERAGE_PPM = &H15         PRINTER_NOTIFY_FIELD_TOTAL_PAGES = &H16         PRINTER_NOTIFY_FIELD_PAGES_PRINTED = &H17         PRINTER_NOTIFY_FIELD_TOTAL_BYTES = &H18         PRINTER_NOTIFY_FIELD_BYTES_PRINTED = &H19         PRINTER_NOTIFY_FIELD_OBJECT_GUID = &H1A     End Enum     Public Enum Job_Notify_Field_Indexes         JOB_NOTIFY_FIELD_PRINTER_NAME = &H0         JOB_NOTIFY_FIELD_MACHINE_NAME = &H1         JOB_NOTIFY_FIELD_PORT_NAME = &H2         JOB_NOTIFY_FIELD_USER_NAME = &H3         JOB_NOTIFY_FIELD_NOTIFY_NAME = &H4         JOB_NOTIFY_FIELD_DATATYPE = &H5         JOB_NOTIFY_FIELD_PRINT_PROCESSOR = &H6         JOB_NOTIFY_FIELD_PARAMETERS = &H7         JOB_NOTIFY_FIELD_DRIVER_NAME = &H8         JOB_NOTIFY_FIELD_DEVMODE = &H9         JOB_NOTIFY_FIELD_STATUS = &HA         JOB_NOTIFY_FIELD_STATUS_STRING = &HB         JOB_NOTIFY_FIELD_SECURITY_DESCRIPTOR = &HC         JOB_NOTIFY_FIELD_DOCUMENT = &HD         JOB_NOTIFY_FIELD_PRIORITY = &HE         JOB_NOTIFY_FIELD_POSITION = &HF         JOB_NOTIFY_FIELD_SUBMITTED = &H10         JOB_NOTIFY_FIELD_START_TIME = &H11         JOB_NOTIFY_FIELD_UNTIL_TIME = &H12         JOB_NOTIFY_FIELD_TIME = &H13         JOB_NOTIFY_FIELD_TOTAL_PAGES = &H14         JOB_NOTIFY_FIELD_PAGES_PRINTED = &H15         JOB_NOTIFY_FIELD_TOTAL_BYTES = &H16         JOB_NOTIFY_FIELD_BYTES_PRINTED = &H17     End Enum #End Region     Public Sub New()         '\ As it stands, version is always 2         dwVersion = 2         '\ We must have at least one notification - status makes sense to test with...         'NotifyJobStatus = True         FieldCount = 1         Dim pfld1 As Short = Job_Notify_Field_Indexes.JOB_NOTIFY_FIELD_STATUS         '\ Use pointer to array per your suggestion...         pFields = Marshal.AllocHGlobal(2)         Marshal.WriteInt16(pFields, 0, pfld1)     End Sub End Class

And when I pass it to FindFirstPrinterChangeNotification it goes OK but when a print job occurs and the wait object triggers I have to call FindNextPrinterChangeNotification to get the info that has changed which I have declared thus:-

<DllImport("winspool.drv", EntryPoint:="FindNextPrinterChangeNotification", _     SetLastError:=True, CharSet:=CharSet.Ansi, _     ExactSpelling:=True, _     CallingConvention:=CallingConvention.StdCall)> _     Public Shared Function FindNextPrinterChangeNotification _                             (<InAttribute()> ByVal hChangeObject As IntPtr, _                              <OutAttribute()> ByRef pdwChange As IntPtr, _                              <InAttribute()> ByVal pPrinterNotifyOptions As PrinterNotifyOptions, _                              <OutAttribute()> ByRef lppPrinterNotifyInfo As IntPtr _                                  ) As Boolean     End Function

Now when this is called the variable pdwChange is filled with the correct value to indicate what has changed but lppPrinterNotifyInfo is never non-zero.

Any thoughts at all?

Thanks in advance,
Duncan

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