private void GroupQuad_OnClick(GroupControl sender)
 {
     string[] oct = { "Q1", "Q2", "Q3", "Q4" };
     for (int i = 0; i < oct.Length; i++)
     {
         if (sender.Text == oct[i])
         {
             nation1.Team         = matchesOct[i].TeamA;
             nation2.Team         = matchesOct[i].TeamB;
             nation3.Team         = null;
             nation4.Team         = null;
             dataGrid.ItemsSource = matchesOct;
         }
     }
 }
        private void Group_OnClick(GroupControl sender)
        {
            List <Match> matches = matchesPlayOff.Where(match => match.Tag == sender.Text).ToList();
            List <Team>  team    = new List <Team>();

            foreach (Match match in matches)
            {
                if (team.Find(t => t.Code == match.TeamA.Code) == null)
                {
                    team.Add(match.TeamA);
                }
                if (team.Find(t => t.Code == match.TeamB.Code) == null)
                {
                    team.Add(match.TeamB);
                }
            }
            nation1.Team = team[0];
            nation2.Team = team[1];
            nation3.Team = team[2];
            nation4.Team = team[3];

            dataGrid.ItemsSource = matches;
        }