I have a binding that uses this collection:

```
private RangeObservableCollection<Item> _allItems;

public RangeObservableCollection<Item> AllItems
            { 
                get { return _allItems; }
                set { _allItems = value; }
            }

```

RangeObservarbleCollection is a collection that throws only one notification that the collection was changed when AddRange method is called.

I have another collection whose items depend on the items of the AllItems collection. 

```
private RangeObservableCollection<Item> _commonItems;

```

I want whenever the AllItems collection gets changed to fire a method that does some calculations and changes the items in the CommonItems collection. I tried to fire it inside the set method for the AllItems collection but the Value is of type collection not of type Item.