visa bilder med en popup!

Jag har två php sidor som jag använder för att visa bilder.
thumbs.php och show.php
i thumbs.php så visas alla thumbs från en mapp - trycker man på en bild så kommer man till show.php

Jag skulle vilja att show.php kom upp i ett popupfönster istället.
Alla funktioner hämtas från en functions.inc

thumbs.php

function show_thumbs($cols, $th_width, $th_height, $cellpadding, 
                     $cellspacing, $perpage)
{
  $dir = $_GET["dir"];
  $tot = count_files($dir);
  if (isset($_GET["page"])) {
    $page = $_GET["page"];
  }  
  if (isset($_GET["img"])) {
    $img = $_GET["img"];
  }
  global $showfilename;
  global $hidefilenameext;
  
  if ($page == NULL) {
    $page = ceil($img  / $perpage);
  }
  
  echo "<div style='text-align: center'>";
  echo "<table border='0' cellpadding='$cellpadding' 
        cellspacing='$cellspacing' align='center'>\n";
  echo "<tr>\n";
         
  $filelist = list_files("./$dir/thumbs");
  $n = 1;
  
  $end = min(($page * $perpage), sizeof($filelist));

  for ($i = (($page - 1) * $perpage);  $i < $end; $i++) 
  {
    echo "<td align='center'>\n";    
    echo "<table border='0' cellspacing='1' cellpadding='0' 
          bgcolor='#F8F8F8'>\n";
    echo "<tr><td>\n";
    echo "<a href='show.php?dir=$dir&tot=$tot&img=".($i + 1).
         "&page=$page'>\n";
    echo "<img src='$dir/thumbs/$filelist[$i]' width='$th_width' 
               height='$th_height' border='0'><br>\n";
    echo "</a>\n";
    echo "</td></tr>\n";
    echo "</table>\n";
    
    if ($showfilename) 
    {
      if ($hidefilenameext) {
        echo "<small>".substr($filelist[$i], 0, strrpos($filelist[$i], '.'))."</small>";
      }
      else
      {
        echo "<small>$filelist[$i]</small>";
      }     
    }
    
    echo "</td>\n"; 

    if (($n % $cols) == 0 && ($n != $perpage)) 
    {
      echo "</tr>";
      echo "<tr align='center'>";
    }
    
    $n++;
  }
  echo "</tr>\n";    
  echo "</table>";
 
  // We need to show thumbs in more than one page
  if (sizeof($filelist) > $perpage) {
    echo ("Page:&nbsp;");
    
    for ($j = 1; $j <= ceil(sizeof($filelist) / $perpage); $j++) {
     echo ("<a href='thumbs.php?dir=$dir&page=".$j."'>");
     
     // Current page   
     if ($page == $j) {
       echo "<b>".$j."</b>";
     }
     else 
     {
       echo $j;
     } 
      
     echo "</a>";
     echo ("&nbsp;&nbsp;");
    }
  
    echo "<br><br>";  
  }

  echo "<a href='index.php'>Album</a>&nbsp;"; 
  
  echo "</div>";
 }

show.php

function show_picture()
{
  $dir = $_GET["dir"];
  $tot = $_GET["tot"];
  $img = $_GET["img"];

  echo "<div style='text-align: center'>";
  echo "<big>\n";
  
  if ($img  > 1)
  {
    echo "<a href='show.php?dir=$dir&tot=$tot&img=".($img - 1)."'>&lt;&lt;</a>"; 
  }

  echo "&nbsp;&nbsp;&nbsp\n";
  echo "</big>\n";
  echo "<b>".$img."</b> of ".$tot; 
  echo "&nbsp;&nbsp;&nbsp\n";
  echo "<big>\n";

  if ($img < $tot)
  {
    echo "<a href='show.php?dir=$dir&tot=$tot&img=".($img + 1)."'>&gt;&gt;</a>"; 
  }

  echo "</big>\n";
  echo "<br><br>\n"; 
  
  echo "<table border='0' cellspacing='1' cellpadding='0' 
               bgcolor='#F8F8F8' align='center'>\n";
  echo "<tr><td>\n";
  echo "<a href='thumbs.php?dir=$dir&img=$img'>"; 
  echo "<img src='$dir/".search_file("./$dir", $img)."' border=0 
        onLoad='resize(this);' name=foto 
        alt='Click to go to thumbnails page.'>";
  echo "</a>";        
  echo "</td></tr>\n";
  echo "</table>\n";

  
  echo "<br><br>\n"; 
  echo "<big>\n";
  
  if ($img > 1)
  {
    echo "<a href='show.php?dir=$dir&tot=$tot&img=".($img - 1)."'>&lt;&lt;</a>"; 
  }
  
  echo "&nbsp;&nbsp;&nbsp\n";
  
  if ($img  < $tot)
  {
    echo "<a href='show.php?dir=$dir&tot=$tot&img=".($img + 1)."'>&gt;&gt;</a>"; 
  }

  echo "</big>\n";
  echo "<br><br>\n"; 

  echo "<a href='index.php'>Album</a>&nbsp; - &nbsp;"; 
  echo "<a href='thumbs.php?dir=$dir&img=$img'>Bilder</a>";  
    
  echo "<br><br>\n"; 
  
  echo "</div>"; 
}

?>