Question

I have an application that uses Caliburn.Micro. My View contains a user control which contains e.g. a tab control. I want to be able to access that tab control from the outer ViewModel to select a particular tab. Is it possible?
Thanks.

Answer 1

The standard MVVM way is to have the TabControls SelectedItem property bound to a property on your viewModel.

<TabControl ItemsSource="{Binding PropertyToYourViews}"
            SelectedItem="{Binding PropertyToYourSelectedView}">

 </TabControl>

If you do it this way your ViewModel does not have to know about the existence of the TabControl.

The next step is dependant on your implementation. Your outer ViewModel could simply keep a reference to the child viewModels SelectedView property and access it directly however,
If you want to keep your ViewModels decoupled then you will need to implement some sort of notification system. I’m not sure of the specifics of Caliburn.Micro but most MVVM frameworks offer some kind of solution for this.