Global $mainwindow
Global $childwin1
Global $Button_Main1
Global $Button_Child1


_main()

Func _main()
  $mainwindow = GUICreate("Test", 340, 500)
  $Button_Main1 = GUICtrlCreateButton("Öffne Dialog", 20, 20, 100, 50)

  GUISetState()
  While 1
    Switch GUIGetMsg()
        Case -3
            exit
        Case $Button_Main1
			_Childwin1()
    EndSwitch
  WEnd
EndFunc

Func _Childwin1()
  $childwin1 = GUICreate("Child GUI", 350, 350, 100, 100, -1, -1, $mainwindow)
  $Button_Child1 = GUICtrlCreateButton("Mach Was", 20, 20, 100, 50)
  
  GUISetState()
  
  While 1
    Switch GUIGetMsg()
        Case -3
            GUIDelete()
        Case $Button_Child1
            _MachWas("Hallo")
		EndSwitch
  WEnd
EndFunc

Func _MachWas($Ausgabetext)
  MsgBox(0,"Info",$Ausgabetext)
EndFunc