Hello Valentina,

Thank you for the code-snippet and the description you have provided in regards to the selection logic you are looking for.

When MVVM is used, in order to prompt the user with a message for whether or not the current item's changes should be kept or discarded when changing the selected item, I can suggest you use a Behavior by handling the SelectedItemChanged event of the XamComboEditor. This would also require having an additional property that keeps the old value of the property that was changed. This will allow us to revert to it whenever the user decides to discard the changes.

ViewModel.Item:

public class Item
{
    public string Name { get; set; }
    public string OldName
    {
        get { return oldName; }
        set
        {
            // Set OldName only if it is not currently set or it should be reset.
            // This way only its first set is kept prior to the reset.
            if (oldName == null || (oldName != null && value == null))
                oldName = value;
        NotifyPropertyChanged("OldName");
        }
    }
}

Behavior event:

private void AssociatedObject_SelectedItemChanged(object sender, System.Windows.RoutedPropertyChangedEventArgs<object> e)
{
    var previousItem = e.OldValue as Item;
    if (previousItem == null)
        return;

    if (previousItem.OldName != null)
    {
        if (MessageBox.Show("The 'Name' of '" + previousItem.OldName + "' Item was modified. Do you accept the changes?", "Changes", MessageBoxButton.YesNo) == MessageBoxResult.Yes)
        {
            previousItem.OldName = null;                    
        }
        else
        {
            previousItem.Name = previousItem.OldName;
            previousItem.OldName = null;
            AssociatedObject.SelectedItem = e.OldValue;
        }
    }
}

View:

<igEditors:XamComboEditor x:Name="combo" ... >
    <i:Interaction.Behaviors>
        <behaviors:XamComboEditorBehavior />
    </i:Interaction.Behaviors>
</igEditors:XamComboEditor>

I have attached a sample application that demonstrates the approach from above.

If you have any questions, please let me know.