function view_page(id,cur){
  var el=document.getElementById('nav_block_'+id);
  if (el!=null){
    document.getElementById('nav_block_'+cur).style.display='none';
    el.style.display='block';
  }  
}

function Open_bookmark(id,title){ 
  for(var i=1;i<4;i++){
    document.getElementById('main_header_'+i).className="off-index-link";
    document.getElementById('main_content_'+i).style.display="none";
  }
  //title.onclick='function(){Open_bookmark('+id+',this);}';
  title.className="";
  document.getElementById('main_content_'+id).style.display="block";
}