Private Sub Worksheet_Activate()
Dim vrtFeuille As Variant, Item As Variant
With ListBox1
If Not .Value = Empty Then
.Selected(0) = True
Do While .ListCount > 0
.RemoveItem (.ListIndex)
Loop
Else
For Each vrtFeuille In ThisWorkbook.Sheets
.AddItem vrtFeuille.Name
Next vrtFeuille
End If
End With
ThisWorkbook.Sheets(1).Activate
End Sub