I have a view that has 2 combo boxes (Call them ParentTypeCombo and ChildTypeCombo). Both of these combo boxes have the same backing drop down list (call it WorkItemTypes).
Using MVVM how can I know when the value was changed for these combo boxes? I have bound them to properties (Call them ParentType and ChildType). But as I recall, my setter will not be called by WPF.
I don't want to just go off the event on the combo box because that will go in the code behind, not the View Model.
(I saw an example using an ObservableCollection. But I confess I did not understand it. I used a value called CollectionViewSource that it does not explain what is or where it is obtained.)