Vb

Public Class Form1
Dim t() As Char
Dim i As Byte
Dim a As String

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.StartPosition() = FormStartPosition.CenterScreen
Séction.Items.Add("Administration")
Séction.Items.Add("Jury")
ToolTip1.ShowAlways = True
Me.StartPosition = FormStartPosition.CenterParent
End Sub

Private Sub Séction_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Séction.SelectedIndexChanged
If Séction.Text = "Administration" Then
Formateur.Text = ""
pw.Items.Clear()
Formateur.Items.Clear()
Formateur.Items.Add("x")
pw.Items.Add("x1")
Formateur.Items.Add("xx")
pw.Items.Add("xx2")
Formateur.Items.Add("xxx")
pw.Items.Add("xxx3")
Formateur.Items.Add("xxxx")
pw.Items.Add("xxxx4")
ElseIf Séction.Text = "Jury" Then
Formateur.Text = ""
Formateur.Items.Clear()
pw.Items.Clear()
Formateur.Items.Add("y")
pw.Items.Add("y1")
Formateur.Items.Add("yy")
pw.Items.Add("yy2")
Formateur.Items.Add("yyy")
pw.Items.Add("yyy3")
End If
End Sub

Private Sub psw_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles psw.TextChanged
a = pw.Items(Formateur.SelectedIndex)
psw.MaxLength = a.Length
If psw.Text.Length = a.Length Then
Timer1.Enabled = True
End If
If psw.Text <> "" Then
ErrorProvider1.Clear()
End If
End Sub
Private Sub Label5_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label5.MouseMove
ToolTip1.SetToolTip(Label5, "Mot de passe de l'utilisateur")
End Sub
Private Sub Label4_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label4.MouseMove
ToolTip1.SetToolTip(Label4, "Le nom de l'utilisateur")
End Sub
Private Sub Label3_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label3.MouseMove
ToolTip1.SetToolTip(Label3, "Le domaine de l'utilisateur")
End Sub
Private Sub Utilisateur_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Formateur.SelectedIndexChanged
psw.Focus()
End Sub
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
i += 5
ProgressBar1.Value = i
If i = 100 Then
If psw.Text.ToUpper = pw.Items(Formateur.SelectedIndex) Then
Form1.Show()
Me.Hide()
Else
ErrorProvider1.SetError(psw, "Mot de passe incorrecte")
End If
Timer1.Stop()
i = 0
ProgressBar1.Value = 0
End If
End Sub
End Class

NB :
séction : Combobox
Formateur : Combobox
Psw : Textbox
Pw : Listbox