vbNormal
vbNormalFocus
vbNormalNoFocus
vbMaximized
vbMaximizedFocus
vbMinimized
vbMinimizedFocus
vbMinimizedNoFocus

'zunächst die benötigten API-Deklarationen
Private Declare Function ShellExecute Lib "shell32.dll" _
    Alias "ShellExecuteA" (ByVal hWnd As Long, _
    ByVal lOperation As String, _
    ByVal lpFile As String, _
    ByVal lpParameters As String, _
    ByVal lpDirectory As String, _
    ByVal nShowCmd As Long) As Long
 
Private Declare Function GetSystemDirectory Lib "kernel32" _
  Alias "GetSystemDirectoryA" (ByVal lpBuffer As String, _
  ByVal nSize As Long) As Long
 
Private Declare Function GetDesktopWindow Lib "user32" () _
  As Long
 
Private Const SE_ERR_NOASSOC = 31
Private Const SE_ERR_NOTFOUND = 2
 
'Dokument öffnen und ggf. autom. den
'"Öffnen mit..." - Dialog anzeigen
Private Sub DocumentOpen(sFilename As String)
  Dim sDirectory As String
  Dim lRet As Long
  Dim DeskWin As Long
 
  DeskWin = GetDesktopWindow()
  lRet = ShellExecute(DeskWin, "open", sFilename, _
    vbNullString, vbNullString, vbMaximizedFocus)
 
  If lRet = SE_ERR_NOTFOUND Then
    'Datei nicht gefunden
 
  ElseIf lRet = SE_ERR_NOASSOC Then
    'Wenn die Dateierweiterung noch nicht bekannt ist...
    'wird der "Öffnen mit..."-Dialog angezeigt.
    sDirectory = Space(260)
    lRet = GetSystemDirectory(sDirectory, Len(sDirectory))
    sDirectory = Left(sDirectory, lRet)
    Call ShellExecute(DeskWin, vbNullString, _
      "RUNDLL32.EXE", "shell32.dll,OpenAs_RunDLL " & _
      sFilename, sDirectory, vbNormalFocus)
  End If
End Sub
 
Private Sub Command1_Click()
DocumentOpen "C:\Test.doc"
End Sub