my @col = (40,$center-35,$center+30,$breed-40);
  my @row = (20,40,60,80,90,110);

##</code><code>##

#!perl
use strict;
use warnings;
use 5.010;
use Tk;
printf "Tk::VERSION %s\n",$Tk::VERSION;

# Declarations
my $breed = 400; # width
my $hoog  = 200; # height
my $netspdx = 1;
my $netspdy = 0;
my $netuse  = 0.05;
my $fsizex  = 3;
my $fsizey  = 0;

my $mw = new MainWindow(
   -height => $hoog,
   -width  => $breed,
   -title  => 'Downloadtime estimator'
);

init();
MainLoop;

sub init {
  my $center = $breed/2;
  my @col = (40,$center-35,$center+30,$breed-40);
  my @row = (20,40,60,80,90,110);
  my @speed = ( undef,
    ['Gb',1000000000],
    ['Mb',1000000],
    ['kb',1000],
  );
  my @button = ();
   
  # Row 0
  my $y = $row[0];  
  $mw->Label(-text=>"Fill in the fields and check the right boxes")
             ->place( -x=>$center, -y=>$y, -anchor=>'center' );

  # Row 1
  $y = $row[1];               
  $mw->Label(-text=>"Network speed")
             ->place( -x=>$col[0], -y=>$y, -anchor=>'w' );
             
  $mw->Entry( -justify=>'right',-textvariable=> \$netspdx, -width=>5 )
             ->place( -x=>$center, -y=>$y, -anchor=>'center' );
            
  my $x = $col[2];
 
  for my $i (1..3){ 
    $button[$i] = $mw-> Radiobutton(
           -variable=> \$netspdy, 
           -text    => $speed[$i][0], 
           -value   => $speed[$i][1]) 
     -> place( -x =>$x, -y=>$y, -anchor=>'w' );
    $x += 50;
  }
  $button[1]->select();	

  # Row 2
  $y = $row[2];
  $mw->Label( -text=>"Avg network use in %" ) 
     ->place( -x=>$col[0], -y=>$y, -anchor=>'w' );
  $mw->Entry( -textvariable=> \$netuse, -width => 5, -justify => 'right',  )          
     ->place( -x=>$center, -y=>$y, -anchor=>'center' );
  
  # Row 3
  $y = $row[3];
  $mw->Label( -text=>"File size" )                                            
     ->place( -x=>$col[0], -y=>$y, -anchor=>'w' );
  $mw->Entry(
         -textvariable=> \$fsizex,
         -width => 5,
         -justify=>'right'
)          
     ->place( -x=>$center, -y=>$y, -anchor=>'center' );
   
  $x = $col[2];   
  for my $i (1..3){ 
    $button[$i+3] = $mw-> Radiobutton(
          -variable=> \$fsizey, 
          -text    => uc $speed[$i][0], 
          -value   => $speed[$i][1]) 
     ->place( -x=>$x, -y=>$y, -anchor=>'w' );
    $x += 50;
  }  
  $button[4]->select();  
  
  # Row 5
  $y = $row[5];
  $mw->Label( -text=>"Estimated time" ) 
     ->place( -x=>$col[0], -y=>$y, -anchor=>'w' );
      
  my $result = $mw->Label( -text=>'' ) 
                  ->place( -x=>$center, -y=>$y, -anchor=>'center' ); 
               
  my $units = $mw->Label( -text=>'' ) 
                  ->place( -x=>$col[2], -y=>$y, -anchor=>'w' );

  # Row 6      
  $y = $hoog-50;

  # OK button
  $mw->Button( -text  => "Okay", 
               -width => 10,
               -command => [\&Calc,$result,$units] ) 
     ->place( -x=>$center-100, -y=>$y );

  # Exit button
  $mw->Button(-text  => "Exit", 
              -width => 10,
              -command => sub { exit }) 
     ->place( -x=>$center+100, -y=>$y );
}

sub Calc { 
  my ($result,$units) = @_;
  my $time =  $fsizex*$fsizey  /  ($netspdx*$netspdy/100*$netuse);
  my $text = 'Seconds';
  if ($time > 60){
    $time = $time / 60;
    $text = 'Minutes';
    if ($time > 60){
      $time = $time / 60;
      $text = 'Hours';
      if ($time > 24){
        $time = $time / 24;
        $text = 'Days';
      }
    };
  } 
  $units->configure(-text=>$text);
  $result->configure(-text=>sprintf "%.2f",$time);
};