use Tk;
#================================================
#		Main-Window
#================================================
  $HF = new MainWindow (-title => "Main-Window");
  $HF->geometry('100x100');

#==================================================
#		Buttons
#==================================================
  $BtnStart = $HF->Button
  (
  -text=>"START", 
  -command => \&ext,
  -borderwidth => 2,
  -relief => raised,
  )->pack();


  $BtnStop  = $HF->Button
  (
  -text=>"STOP  ",
  -command => sub{close (FH);$HF->update();},
  )->pack();

#================================================
# Tk-End
#================================================
  MainLoop();

#================================================
# SUB-Programs
#================================================
  sub ext
  {
        #xxxx Pipe to the external programm
	open(FH, "c:\\extern.exe |");

	while($tp=<FH>)
	{
		print "\n$tp";
		$HF->update();
	}
  }