Question about ViewModel Management (DesignTime Vs Run Time)

Question

I have a fairly basic WPF UI whereby user requests cause a new tab to open in my TabControl. The TabControl is bound to an ObservableCollection

Answer 1

Yes I think it will interfere with your current setup

The ViewModelLocator is a static class that returns a dummy object at design time, and a static ViewModel at runtime. This means that

• The ViewModelLocator, not your ParentViewModel, contains your TabViewModels

• You cannot have multiple instances of the same Tab (ViewModel) open at once

• You cannot manage Open/Closed tabs unless you reference the UserControl, which is a violation of the MVVM principle where the ViewModel doesn't know of the View

• You can't instantiate new copies of the TabViewModel with parameterized constructors. For example, OpenTabs.Add(new CustomerViewModel(CustomerId));

Perhaps an alternative could be a Converter? One that returns a static object if in design time, or the bound object during runtime? I've never tested such a thing but in theory it should work :)