function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } 
  else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

addLoadEvent( function(){ add_print_link( 'nav' ) } );

function add_print_link( id ){
  if(!document.getElementById || !document.getElementById(id)) {
    return;
  }

  // add extra functions to page tools list
  var print_page = document.getElementById( id );

  // create print link
  var print_function = document.createElement('p');
  print_function.className = 'print-link';
  print_function.onclick = function(){ print_preview(); return false; };
  print_function.appendChild( document.createTextNode( 'Print the Page' ) );
}

function print_preview() {
  // Switch the stylesheet
  //setActiveStyleSheet('Print Preview');
	
  // Create preview message
  //add_preview_message();

  // Print the page
  window.print();
}

function add_preview_message(){
  var main_content = document.getElementById('content');
  var main_body = main_content.parentNode;

  if (document.getElementById){
    var preview_message = document.createElement('div');
    preview_message.id = 'preview_message';
	
    // Create Heading
    var preview_header = document.createElement('h3');
    var preview_header_text = document.createTextNode('This is a print preview of this page');
    preview_header.appendChild(preview_header_text);
		
    // Create paragraph
    var preview_para = document.createElement('p');
    var preview_para_text = document.createTextNode('Without this message of course. ');
		
    var cancel_function_link = document.createElement('a');
    cancel_function_link.onclick = function(){ cancel_print_preview(); return false; };
    cancel_function_link.setAttribute('href', '#');	
    var cancel_function_link_text = document.createTextNode('Return to the existing page.');
    cancel_function_link.appendChild(cancel_function_link_text);
    preview_para.appendChild(preview_para_text); //
    preview_para.appendChild(cancel_function_link);
		
    // Put it all toegether
    preview_message.appendChild(preview_header); 
    preview_message.appendChild(preview_para);
    main_body.insertBefore(preview_message, main_content);
  }
}

function cancel_print_preview() {
  // Destroy the preview message
  var print_preview = document.getElementById('preview_message');
  var main_body = print_preview.parentNode;
  main_body.removeChild(print_preview);
	
  // Switch back stylesheet
  setActiveStyleSheet('default');
}

function setActiveStyleSheet(title) {
  var i, a, main;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title")) {
      a.disabled = true;
      if(a.getAttribute("title") == title) {
        a.disabled = false;
      }
    }
  }
}