Private Sub TabControl1_Click(ByVal sender As Object, ByVal e As _
  System.EventArgs) Handles TabControl1.Click
        Dim f As Form
        Const PROJECTNAME As String = "WindowsApplication1" ' MUSST DU ANPASSEN 
        ' !!!
        Dim casm As System.Reflection.Assembly = _
          System.Reflection.Assembly.GetExecutingAssembly
        If Me.TabControl1.SelectedTab Is Me.TabPage1 Then
            f = CType(casm.CreateInstance(PROJECTNAME & ".Form1"), Form)
        ElseIf Me.TabControl1.SelectedTab Is Me.TabPage2 Then
            f = CType(casm.CreateInstance(PROJECTNAME & ".Form2"), Form)
        ElseIf Me.TabControl1.SelectedTab Is Me.TabPage3 Then
            f = CType(casm.CreateInstance(PROJECTNAME & ".Form3"), Form)
        End If
        f.ShowDialog()
        f.Dispose()
 
    End Sub