Voila un code qui devrai te convenir a peu pres
Dim strDatei As String
Dim strDatei2 As String
strDatei = Application.GetOpenFilename(filefilter:="Excel projects (*.xls), *.xls", Title:="Save the project as..." )
' Regarde les documents deja ouvert
strDatei2 = GetFileName(strDatei)
findit = False
i = 1
While i <= Workbooks.Count And Not findit
If Workbooks.Item(i).name = strDatei2 Then
findit = True
Else
i = i + 1
End If
Wend
If findit Then
' si deja ouvert, on le réactive juste
Workbooks.Item(i).Activate
Else
' si non , on l'ouvre
Workbooks.Open strDatei2
End If