I am have one js function for all my pages that are using a popup
window to display a larger image from a thumbnail. The problem
is when the user clicks on another thumbnail without closing the
previous window. When this happens, no window is displayed
since it is already displayed and the image is added to the
previous popup.

What I need is the function to close the popup window if it is
open. Then re-open it with a new large image.
This is what I have...
Code:
function Display(obj,sSize) {
  shutdown();
  DispWin=window.open('','NewWin','toolbar=no,status=no,' + sSize + ',resizable=no,scrollbars=no,top=100px,left=200px');
  dtitem="<html><head><title>Test</title>";
  dtitem+="<style type='text/css'>html {margin:0px;padding:0px;} body {margin:0px; padding:0px; border:0px;}</style></head><body>";
  dtitem+="<img src='http://www.somewhere.com/images/"+obj+"' border='0'><br>";
  dtitem+="<center><a href='javascript: window.close();'><font face='verdana, helvetica, arial' size='2'>Close Window</font></a></center></body></html>";
  DispWin.document.write(dtitem);
}


function shutdown() {
  DispWin.document.close();
  DispWin.close();
}
Thanks in advance for any assistance.