Binding multiple ComboBoxes to the same collection and using Filters

When multiple ComboBoxes bind to the same collection and the collection uses a Filtering, the items of all ComboBoxes get filtered. Not as expected only the one using the filter. If a ComboBox already has a value selected and another ComboBox uses a filter on the collection, the first ComboBox could lose its value because the SelectedItem is no longer contained in the displayed list.

This hapens because in WPF all Collections contain a default ICollectionView. This view can be retrieved with:

var view = CollectionViewSource.GetDefaultView(collection);

This can easily be handled if each ComboBox binds to a unique ICollectionView. It doesn't matter if the underlying Collection is the same as long as the ICollectionViews differ.

IList<ComboBoxExtDataObject> _dataObjects;
public IList<ComboBoxExtDataObject> DataObjects
{
    get
    {
        if (_dataObjects == null)
        {
            _dataObjects = new ObservableCollection<ComboBoxExtDataObject>();

            for (int i = 1; i <= 50; i++)
                _dataObjects.Add(new ComboBoxExtDataObject { Id = i, Name = "Name" + i });
        }
        return _dataObjects;
    }
}

ICollectionView _sources1;
public ICollectionView Sources1
{
    get
    {
        if (_sources1 == null)
        {
            var lst = new CollectionViewSource();
            lst.Source = _dataObjects;
            _sources1 = lst.View;
        }
        return _sources1;
    }
}

ICollectionView _sources2;
public ICollectionView Sources2
{
    get
    {
        if (_sources2 == null)
        {
            var lst = new CollectionViewSource();
            lst.Source = _dataObjects;
            _sources2 = lst.View;
        }
        return _sources2;
    }
}

In this case I bind the ComboBox1 to Sources1 and the ComboBox2 to Sources2. Now I can easily use the Filtering that I added to my ComboBox without changing the CollectionView of the other ComboBox.