#!/usr/bin/perl -w
use Tk;
use Tk::Pane;

$mw=MainWindow->new();
$mw->geometry("100x100");
$mw->Button(-text=>"START",-command=>\&start_computation)->pack;

MainLoop;

sub start_computation
	{
	$progress=$mw->Toplevel();
	$progress->geometry("100x100");
	$pane=$progress->Scrolled('Pane',-scrollbars=>'osoe')->pack(-fill=>'both',-expand=>1);
	$text="Computation started...\n";
	$label=$pane->Label(-text=>$text)->pack(-anchor=>'nw');
	
	# doing several computation steps
	foreach$step(1..10)
		{
		sleep(1);
		$text.="Step $step finished.\n";
		$label->destroy;
		$label=$pane->Label(-text=>$text)->pack(-anchor=>'nw');
		$pane->update;
		}
	
	$text.="\nComputation finished.\n";
	$label->destroy;
	$label=$pane->Label(-text=>$text)->pack(-anchor=>'nw');
	$pane->update;
	
	$pane->Button(-text=>"QUIT",-command=>sub{exit;})->pack;
	}