Codice PHP:
Private Sub txtCognome_Utenti_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtCognome_Utenti.TextChanged, txtNome_Utenti.TextChanged, txtUsername_Utenti.TextChanged
If txtCognome_Utenti.Text = String.Empty Or txtUsername_Utenti.Text = String.Empty Or txtNome_Utenti.Text = String.Empty Then
btnAvanti_Panel2.Enabled = False
Else
btnAvanti_Panel2.Enabled = True
End If
End Sub