public void FillData()
        {
            this.listView1.BeginUpdate();

            //Creazione dei gruppi mesi
            this.listView1.Groups.Clear();
            this.listView1.Items.Clear();
            
            this.listView1.ShowGroups = true;
            this.listView1.View = View.Details;

            this.listView1.Columns.Add("");

            ListViewGroup grp = null;

            for (int i = 1; i <= 12; i++)
            {
                grp = new ListViewGroup();
                grp.Name = "MESE" + i.ToString();
                grp.Tag = i;
                grp.Header = System.Globalization.CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName(i);
                this.listView1.Groups.Add(grp);
            }

            //Creazione dei giorni
            DateTime start, end;
            start = new DateTime(2011, 1, 1);
            end = new DateTime(2011, 12, 31);

            ListViewItem elem;

            while (start != end)
            {
                elem = new ListViewItem();
                elem.Text = start.ToLongDateString();
                elem.Tag = start;
                elem.Group = this.listView1.Groups["MESE" + start.Month];
                this.listView1.Items.Add(elem);

                this.listView1.Groups["MESE" + start.Month].Items.Add(elem);

                start = start.AddDays(1);
            }

            this.listView1.Columns[0].AutoResize(ColumnHeaderAutoResizeStyle.ColumnContent);
            this.listView1.EndUpdate();
        }