Declare Function SetParent Lib "user32" (ByVal hWndChild As IntPtr, ByVal _
    hWndNewParent As IntPtr) As IntPtr
    Declare Function SetWindowPos Lib "user32" (ByVal hwnd As IntPtr, ByVal _
    hWndInsertAfter As Int32, ByVal x As Int32, _
                     ByVal y As Int32, ByVal cx As Int32, ByVal cy As Int32, _
                     ByVal wFlags As Int32) As Int32
    Dim WithEvents Btn As New Button With {.Dock = DockStyle.Bottom, .Text = _
    "Start", .Parent = Me}
 
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Me.SetBounds(0, 0, 800, 600)
        Me.CenterToScreen()
        TabControl1.SetBounds(10, 10, 775, 530)
    End Sub
 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
Dim Hnd As IntPtr
hnd = Fensterhandle
        If Hnd <> IntPtr.Zero Then
            SetParent(Hnd, TabControl1.TabPages(0).Handle)
            SetWindowPos(Hnd, 0, 0, 0, TabControl1.TabPages(0).Width, _
              TabControl1.TabPages(0).Height, 0)
        End If
End Sub