Option Explicit
 
Private Declare Function SetParent Lib "user32" _
  (ByVal hWndChild As Long, _
  ByVal hWndNewParent As Long) As Long
 
Dim oForm As Form
 
Private Sub Form_Load()
  <font color=green>' TreeView füllen</font>
  Dim NodeX As Node
 
  With TreeView1.Nodes
    .Add , , "Form2", "Form2"
    .Add , , "Form3", "Form3"
    .Add , , "Form4", "Form4"
  End With
End Sub
 
Private Sub TreeView1_NodeClick(ByVal Node As MSComctlLib.Node)
  If Not oForm Is Nothing Then
    Unload oForm
    Set oForm = Nothing
  End If
 
  Select Case Node.Key
    Case "Form2"
      Set oForm = Form2
    Case "Form3"
      Set oForm = Form3
    Case "Form4"
      Set oForm = Form4
  End Select
 
  <font color=green>' Form positionieren und anzeigen</font>
  With oForm
    SetParent .hWnd, Me.hWnd
    .Move Me.ScaleWidth - .Width, 0
    .Show , Me
  End With
 
  Me.SetFocus
End Sub