Lier deux formulaires d'un même projet

Public Class Elements

    Private mNom As String = String.Empty
    Private mPrenom As String = String.Empty

    Public Property Nom As String
        Get
            Return Me.mNom
        End Get
        Set(value As String)
            Me.mNom = value
        End Set
    End Property

    Public Property Prenom As String
        Get
            Return Me.mPrenom
        End Get
        Set(value As String)
            Me.mPrenom = value
        End Set
    End Property

End Class

Public Class Form1

    Private mFrm2 As New Form2(Me)
    Private mDonnee As Elements

    Private Property Frm2 As Form2
        Get
            Return Me.mFrm2
        End Get
        Set(value As Form2)
            Me.mFrm2 = value
        End Set
    End Property

    Public Property Donnee As Elements
        Get
            If (Me.mDonnee Is Nothing) Then
                Me.mDonnee = New Elements
            End If
            Return Me.mDonnee
        End Get
        Set(value As Elements)
            Me.mDonnee = value
        End Set
    End Property

    Private Sub btnForm2_Click(sender As Object, e As EventArgs) Handles btnForm2.Click
        Frm2.Show()
        Frm2.Donnee = Me.mDonnee
        Me.Hide()
    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Frm2.Show()
        Frm2.Hide()
    End Sub

    Private Sub btnQuitter_Click(sender As Object, e As EventArgs) Handles btnQuitter.Click
        End
    End Sub

    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
        Me.Donnee.Nom = TextBox1.Text
    End Sub

    Private Sub TextBox2_TextChanged(sender As Object, e As EventArgs) Handles TextBox2.TextChanged
        Me.Donnee.Prenom = TextBox2.Text
    End Sub

    Private Sub Form1_Activated(sender As Object, e As EventArgs) Handles Me.Activated

        If (Frm2.Donnee IsNot Nothing) Then
            Me.Donnee = Frm2.Donnee
            Me.TextBox1.Text = Me.Donnee.Nom
            Me.TextBox2.Text = Me.Donnee.Prenom
        End If

    End Sub

End Class

Public Class Form2

    Private mFrm1 As Form1
    Private mDonnee As Elements

    Private Property Frm1 As Form1
        Get
            Return Me.mFrm1
        End Get
        Set(value As Form1)
            Me.mFrm1 = value
        End Set
    End Property

    Public Property Donnee As Elements
        Get
            If (Me.mDonnee Is Nothing) Then
                Me.mDonnee = New Elements
            End If
            Return Me.mDonnee
        End Get
        Set(value As Elements)
            Me.mDonnee = value
        End Set
    End Property

    Public Sub New(ByVal pFrm As Form1)

        ' Cet appel est requis par le concepteur.
        InitializeComponent()

        ' Ajoutez une initialisation quelconque après l'appel InitializeComponent().
        Frm1 = pFrm

    End Sub

    Private Sub btnForm1_Click(sender As Object, e As EventArgs) Handles btnForm1.Click
        Frm1.Show()
        Frm1.Donnee = Me.Donnee
        Me.Hide()
    End Sub

    Private Sub btnQuitter_Click(sender As Object, e As EventArgs) Handles btnQuitter.Click
        End
    End Sub

    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
        Me.Donnee.Nom = TextBox1.Text
    End Sub

    Private Sub TextBox2_TextChanged(sender As Object, e As EventArgs) Handles TextBox2.TextChanged
        Me.Donnee.Prenom = TextBox2.Text
    End Sub

    Private Sub Form2_Activated(sender As Object, e As EventArgs) Handles Me.Activated

        If (Frm1.Donnee IsNot Nothing) Then
            Me.Donnee = Frm1.Donnee
            Me.TextBox1.Text = Me.mDonnee.Nom
            Me.TextBox2.Text = Me.mDonnee.Prenom
        End If

    End Sub

End Class