function change_HP(id,count) {  //function for offer detail menu and layer-visibility
    var menu_sub_string = id.substr(0,id.length-2);
    var item_sub_string = id.substr(0,id.length-2) + 'D'; 
    var myItemCount = id.substr(id.length-2,id.length);
    
    count = count + 1;
    //alert(menu_sub_string + ' ' + item_sub_string + ' ' + myItemCount);
    
    for(i=1;i<count;++i) {
        var menu_element = document.getElementById(menu_sub_string+'0'+i);
        var item_element = document.getElementById(item_sub_string+'0'+i);
        
        menu_element.className = ""; 
        item_element.style.display = "none";
        
        if(i==myItemCount) {
            menu_element.className = "menu_selected";  
            item_element.style.display = "block";
        }
    }
}