my $struct = pack "LLLpLLLpLpLppLIppLLpILL",
     (
      88,                        #'lStructSize'       #  DWORD
      $Handle,                   #'hwndOwner'         #  HWND
      0,                         #'hInstance'         #  HINSTANCE
      $lpstrFilter,              #'lpstrFilter'       #  LPCTSTR
      0,
      0,
#     $lpstrCustomFilter,        #'lpstrCustomFilter' #  LPTSTR
#     length $lpstrCustomFilter, #'nMaxCustFilter'    #  DWORD
#I'm not able to make it work with CustomFilter

      $nFilterIndex,                         #'nFilterIndex'      #  D
+WORD
      $lpstrFile,                #'lpstrFile'         #  LPTSTR
      length $lpstrFile,         #'nMaxFile'          #  DWORD
      $lpstrFileTitle,           #'lpstrFileTitle'    #  LPTSTR
      length $lpstrFileTitle,    #'nMaxFileTitle'     #  DWORD
      $lpstrInitialDir,          #'lpstrInitialDir'   #  LPCTSTR
      $lpstrTitle,               #'lpstrTitle'        #  LPCTSTR
      $Flags,                    #'Flags'             #  DWORD
      0,                         #'nFileOffset'       #  WORD
#      0,                         #'nFileExtension'    #  WORD
      $nFileExtension,           #'nFileExtension'    #  WORD
      $lpstrDefExt,              #'lpstrDefExt'       #  LPCTSTR
      0,                         #'lCustData'         #  DWORD
      0,                         #'lpfnHook'          #  LPOFNHOOKPROC
      $lpTemplateName            #'lpTemplateName'    #  LPCTSTR
      , 0, 1
     );