Declare Auto Function FindWindow Lib "user32" (ByVal lpClassName As String, _
  ByVal lpWindowName As String) As IntPtr
 
 
Declare Auto Function FindWindowEx Lib "user32" (ByVal hWnd1 As IntPtr, _
ByVal hWnd2 As IntPtr, ByVal lpsz1 As String, ByVal lpsz2 As String) As IntPtr
 
 
Declare Function SendMessageByString Lib "user32" Alias "SendMessageA" (ByVal _
  hwnd As IntPtr, _
ByVal uMsg As Int32, ByVal wParam As IntPtr, ByVal lParam As String) As Integer
 
Private Const WM_SETTEXT As Int32 = &HC

 Dim objNotepad As IntPtr = FindWindow("Notepad", Nothing)
 Dim objEdit as IntPtr = FindWindowEx(objNotepad, IntPtr.Zero, "Edit", Nothing)
 
 SendMessageByString(objEdit, WM_SETTEXT, IntPtr.Zero, "das ist notepad!")