Option Explicit
Private Sub CommandButton1_Click()
Dim i As Byte
TextBox1.Value = Range('A1')
Select Case Val(TextBox1)
Case Is < 0
TextBox1.ForeColor = RGB(255, 0, 0) ' police rouge
For i = 1 To 4
Application.Wait Now + TimeValue('00:00:01')
TextBox1.BackColor = RGB(0, 255, 0)
Application.Wait Now + TimeValue('00:00:01')
TextBox1.BackColor = RGB(0, 255, 255)
Next i
Case Is >= 0
TextBox1.ForeColor = RGB(0, 0, 0) 'police noire
End Select
End Sub