Rajouter une mise en forme en cliquant sur la cellule

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
Dim Couleur As Integer
'Jaune 44
'Vert 10
'Bleu  23
'gris 15
If Target.Count > 1 Then Exit Sub
Couleur = Target.Interior.ColorIndex
If Couleur <> 44 And Couleur <> 10 And Couleur <> 23 And Couleur <> 15 Then Exit Sub

If Cells(Target.Row - 1, Target.Column).Borders(xlDiagonalDown).ColorIndex = 3 Then
    Cells(Target.Row - 1, Target.Column).Borders(xlDiagonalDown).LineStyle = xlNone
    Cells(Target.Row - 1, Target.Column).Borders(xlDiagonalUp).LineStyle = xlNone

Else
    With Cells(Target.Row - 1, Target.Column)
        .Borders(xlDiagonalDown).LineStyle = xlContinuous
        .Borders(xlDiagonalDown).Weight = xlMedium
        .Borders(xlDiagonalDown).ColorIndex = 3
        .Borders(xlDiagonalUp).LineStyle = xlContinuous
        .Borders(xlDiagonalUp).Weight = xlMedium
        .Borders(xlDiagonalUp).ColorIndex = 3
    End With
End If
End Sub