Public Class Form1
    Declare Function SetForegroundWindow Lib "user32" (ByVal hwnd As IntPtr) As _
      Int32
    Dim mwh As IntPtr
 
    Private Sub Button1_MouseDown(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles Button1.MouseDown
        Dim p As Process = Process.Start("notepad.exe")
        p.WaitForInputIdle() ' warten bis die Benutzeroberfläche aufgebaut ist
        mwh = p.MainWindowHandle
    End Sub
 
    Private Sub Button2_MouseDown(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles Button2.MouseDown
        SetForegroundWindow(mwh)
        Threading.Thread.Sleep(50)
        SendKeys.Send("Hallo ")
    End Sub
End Class