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( 'Stampa la pagina' ) );

}

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('Anteprima di Stampa');
        preview_header.appendChild(preview_header_text);

        
        // Create paragraph
        var preview_para = document.createElement('p');
        var preview_para_text = document.createTextNode('www.niclor.net  ');
        
        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(' Torna alla pagina originale.');
        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;
     }
   }
}