WPF

<TabItem Header="Durations">

<pre>
<ListBox ItemsSource="{Binding ProjectDurations}">

    <ListBox.ItemTemplate>
        <DataTemplate>

            <StackPanel Orientation="Vertical"
                        Margin="5">

                <TextBlock Text="{Binding BuildingType}"
                            FontSize="14"
                            FontWeight="Bold"/>

                <DataGrid x:Name="projectPacksGrid"
                            AutoGenerateColumns="False" 
                            BorderBrush="SteelBlue"
                            BorderThickness="1"
                            ItemsSource="{Binding Path=Table2}"
                            mcb:DataGridColumnsBehavior.BindableColumns="{Binding Columns2}"/>

            </StackPanel>

        </DataTemplate>
    </ListBox.ItemTemplate>

</ListBox>

/// <summary>
/// Auto-generates the listbox ItemSource, which is a list of data grids
/// </summary>
private void LoadDurationGrid()
{
    if (Project.MaxFloors > 0)
    {
        var durationData = AppCore.BizObject.GetProjectDurationPacks(Project.Id);

        ProjectDurations = new ObservableCollection<ProjectSchedulePackModel>();

        var buildingTypes = BuildingTypes.Where(x => x.NumberOfFloors <= Project.MaxFloors).ToList();

        foreach (var buildingType in buildingTypes)
        {
            List<string> data = new List<string>();

            ProjectSchedulePackModel entity = new ProjectSchedulePackModel
            {
                BuildingType = buildingType.Caption
            };

            var schedulePacks = _schedulePacks.Where(x => x.BuildingTypeId == buildingType.Id).OrderBy(x => x.Sequence).ToList();

            foreach (var schedulePack in schedulePacks)
            {
                var colName = "col" + schedulePack.Id;
                entity.Table2.Columns.Add(colName, typeof(string));
                Binding binding = new Binding(colName);

                DataGridTextColumn column = new DataGridTextColumn
                {
                    Header = schedulePack.Caption,
                    Binding = binding
                };

                entity.Columns2.Add(column);

                var day = durationData.Where(x => x.SchedulePackId == schedulePack.Id).Select(x => x.Days).FirstOrDefault();

                data.Add(day.ToString());
            }

            entity.Table2.Rows.Add(data.ToArray());
            ProjectDurations.Add(entity);
        }
    }
}

public class DataGridColumnsBehavior
{
    public static readonly DependencyProperty BindableColumnsProperty =
        DependencyProperty.RegisterAttached("BindableColumns",
                                            typeof(ObservableCollection<DataGridColumn>),
                                            typeof(DataGridColumnsBehavior),
                                            new UIPropertyMetadata(null, BindableColumnsPropertyChanged));

<pre>
private static void BindableColumnsPropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
{
    DataGrid dataGrid = source as DataGrid;

    ObservableCollection<DataGridColumn> columns = e.NewValue as ObservableCollection<DataGridColumn>;
    dataGrid.Columns.Clear();

    if (columns == null)
    {
        return;
    }

    foreach (DataGridColumn column in columns)
    {
        dataGrid.Columns.Add(column);   // <============   ERROR HERE
    }

    columns.CollectionChanged += (sender, e2) =>
    {
        NotifyCollectionChangedEventArgs ne = e2 as NotifyCollectionChangedEventArgs;
        if (ne.Action == NotifyCollectionChangedAction.Reset)
        {
            dataGrid.Columns.Clear();
            if (ne.NewItems != null)
            {
                foreach (DataGridColumn column in ne.NewItems)
                {
                    dataGrid.Columns.Add(column);
                }
            }
        }
        else if (ne.Action == NotifyCollectionChangedAction.Add)
        {
            if (ne.NewItems != null)
            {
                foreach (DataGridColumn column in ne.NewItems)
                {
                    dataGrid.Columns.Add(column);
                }
            }
        }
        else if (ne.Action == NotifyCollectionChangedAction.Move)
        {
            dataGrid.Columns.Move(ne.OldStartingIndex, ne.NewStartingIndex);
        }
        else if (ne.Action == NotifyCollectionChangedAction.Remove)
        {
            if (ne.OldItems != null)
            {
                foreach (DataGridColumn column in ne.OldItems)
                {
                    dataGrid.Columns.Remove(column);
                }
            }
        }
        else if (ne.Action == NotifyCollectionChangedAction.Replace)
        {
            dataGrid.Columns[ne.NewStartingIndex] = ne.NewItems[0] as DataGridColumn;
        }
    };
}
public static void SetBindableColumns(DependencyObject element, ObservableCollection<DataGridColumn> value)
{
    element.SetValue(BindableColumnsProperty, value);
}
public static ObservableCollection<DataGridColumn> GetBindableColumns(DependencyObject element)

<DataGrid x:Name="dataGridProduit" SelectionMode="Single" AutoGenerateColumns="false"
                  ItemsSource="{Binding MyProducts}" 
                  SelectedItem="{Binding SelectedProduct, Mode=TwoWay}">
<DataGridTextColumn x:Name="Nom" Header="Nom" Binding="{Binding Name, Mode=TwoWay}" Width="*"/>

<TextBox x:Name="tbName" Height="23" Text="{Binding SelectedProduct.Name, Mode=TwoWay}"

<Button x:Name="buttonAdd" Style="{DynamicResource ButtonStyleMainWindow}" Command="{Binding AddCommand}" CommandParameter="{Binding SelectedProduct}" />

 public Class ST
{
   private readonly System.Timers.Timer _timer;
   private DateTime _lastScanTime;
  
 public ST()
        {
            
            _timer = new System.Timers.Timer();
            _timer.Interval = 250;
            _timer.Start();
            _timer.Elapsed += OnTimerElapsed;
        }



         public TimeSpan ScanTime { get; private set; }

          private void OnTimerElapsed(object sender, ElapsedEventArgs e)
        {
            try
            {
                _timer.Stop();
                ScanTime = DateTime.Now - _lastScanTime;
                
                OnValuesRefreshed();
            }
            finally
            {
                _timer.Start();
            }
            _lastScanTime = DateTime.Now;
        }
        
        private void OnValuesRefreshed()
        {
            ValuesRefreshed?.Invoke(this, new EventArgs());
        }
}

private void Window_Loaded(object sender, RoutedEventArgs e)
       {
           _timer = new System.Timers.Timer();
           _timer.Interval = 1000;
           _timer.Elapsed += OnTimerElapsed;
           _timer.Start();

       }

       int i=0;
       private void OnTimerElapsed(object sender, ElapsedEventArgs e)
       {
           i++;

           label1.Content = i.ToString();

       }

label1.Content = i.ToString();

<Label x:Name="label1"  HorizontalAlignment="Center" Margin="2" VerticalAlignment="Center" Height="79" Width="86"/>