The CurrencyManager.ItemChanged event will occur when the user calls the BindingManagerBase.ResumeBinding or BindingManagerBase.SuspendBinding method.
The CurrencyManager.ItemChanged event occurs only when the item itself has been changed in some manner. For example, if the value of an item is changed from 10 to 42, the event will occur. This should not be confused with the BindingManagerBase.PositionChanged event where the item has been changed to a new item.
The event will also occur if the underlying data changes. For example, if you change the value of a System.Data.DataRowView, the CurrencyManager.ItemChanged event will occur.
If you are creating your own control that uses the System.Windows.Forms.CurrencyManager, you should use the System.ComponentModel.IBindingList.ListChanged instead of the CurrencyManager.ItemChanged event. The System.ComponentModel.ListChangedEventArgs.ListChangedType property of the System.ComponentModel.ListChangedEventArgs enables you to determine the type of action that has occurred.
For more information about handling events, see Consuming Events.