Public Class Form1
 
    ' benötigte API-Deklarationen
    Private Declare Function SetWindowLong Lib "user32" _
      Alias "SetWindowLongA" ( _
      ByVal hwnd As IntPtr, _
      ByVal nIndex As Integer, _
      ByVal dwNewLong As Integer) As Integer
 
    Private Declare Function SetParent Lib "user32" ( _
      ByVal hWndChild As IntPtr, _
      ByVal hWndNewParent As Integer) As Integer
 
    Private Declare Function GetWindowLong Lib "user32" _
      Alias "GetWindowLongA" ( _
      ByVal hwnd As IntPtr, _
      ByVal nIndex As Integer) As Integer
 
    Private Declare Function GetParent Lib "user32" _
      Alias "GetParent" ( _
      ByVal hwnd As IntPtr) As Integer
 
    Private Const WS_EX_MDICHILD = &H40&
    Private Const WS_EX_WINDOWEDGE = &H100&
    Private Const GWL_EXSTYLE = (-20)
 
    Private nOldStyle As Integer
    Private nOldParent As Integer
 
 
    Private myhWndChild As IntPtr
    Private myhWndMDI As IntPtr
 
    Private myProcess As Process                'Zum Starten eines Externen 
    ' Programmes
 
    ' beliebiges Fenster als Child-Form im MDI-Formular anzeigen
    Public Sub MakeChild(ByVal hWndChild As IntPtr, ByVal hWndMDI As IntPtr)
        ' zunächst den Original-Fensterstil und Parent merken
        nOldStyle = GetWindowLong(hWndChild, GWL_EXSTYLE)
        nOldParent = GetParent(hWndChild)
 
        ' jetzt das Fenster zum ChildForm der MDIForm machen
        SetParent(hWndChild, hWndMDI)
        SetWindowLong(hWndChild, GWL_EXSTYLE, WS_EX_MDICHILD Or _
          WS_EX_WINDOWEDGE)
    End Sub
 
 
    'Standart Instalations Pfad
    Private Shared _strProcessExe As String = "notepad.exe"       'Name der 
    ' Ausführungsdatei
    Private Shared _strProcessPfad As String = "C:\Programme\..."      'Pfad 
    ' zur ausführungs Datei ->Ohne abschliesenden Backslash
 
    ''' <summary>
    ''' Name der Ausführungsdatei OHNE den .exe anhang
    ''' </summary>
    Protected ReadOnly Property getProcessExeName() As String
        Get
            On Error Resume Next
            Dim strExeName As String
 
            strExeName = _strProcessExe.Replace(".exe", "")
 
            Return strExeName
        End Get
    End Property
 
 
    Private ReadOnly Property getProcess(Optional ByVal bNotStart As Boolean = _
      True) As Process
        Get
            Try
                'Auslesen aller Prcesse mit dem Keypad Pfad
                Dim processes As Process() = Process.GetProcessesByName( _
                  getProcessExeName)  'Process name ohne .exe angeben
 
                'Prozess überhaubt  vorhanden?
                If processes.Length < 1 And bNotStart = True Then
                    'Wen nicht, jetzt starten
                    'ShowWindow()
 
                    'zurückgeben des gestarteten Process
                    Return Me.myProcess
 
                ElseIf processes.Length > 1 Then
                    'alle überflüssigen wieder beenden
                    'For i As Integer = 1 To processes.Length - 1
                    '    processes(i).Kill()
                    'Next
 
                    'den übriggebliebenen Process zurückgeben
                    Me.myProcess = processes(0)
                    Return Me.myProcess
 
                Else
                    'den einen Process zurückgeben
                    Me.myProcess = processes(0)
                    Return Me.myProcess
                End If
            Catch ex As Exception
                Return Nothing
            End Try
        End Get
    End Property
 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
 
        'Lesse den Process Handle aus
        myhWndChild = getProcess.MainWindowHandle
        myhWndMDI = Me.Handle.ToInt32
 
 
        MakeChild(myhWndChild, myhWndMDI)
 
    End Sub
 
 
    Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        SetWindowLong(myhWndChild, GWL_EXSTYLE, nOldStyle)
        SetParent(myhWndChild, nOldParent)
    End Sub
End Class

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