Sub Macro3()
Dim Bloc As Shape
Dim i As Integer
Dim NouveauTexte As String
NouveauTexte = ActiveCell.Text
With ActiveSheet.Shapes("Bloc").TextFrame
Do While Len(.Characters.Text) > 0
.Characters.Text = ""
Loop
If Len(ActiveCell.Text) <= 255 Then
.Characters.Text = NouveauTexte
Else
For i = 0 To Int(Len(NouveauTexte) / 255)
.Characters(.Characters.Count + 1).Insert Mid(NouveauTexte, (i * 255) + 1, 255)
Next
End If
End With
End Sub