I'm injecting one viewmodel into multiple Viewmodels that are represented as a collection.

So let's say I have a TabControl and each Tab has the same instance of another ViewModel that I display there (this could be a informationBar about something or whatever).

Now It displays only in the most recent tab. So When I look at Tab1 it's there, if I then go to Tab2 it appears there but now never again in Tab1.

Here is the code to reproduce this problem:

public class ShellViewModel : Conductor<TabViewModel>.Collection.OneActive, IShell
{
    public ShellViewModel()
    {
        SameInEveryTabViewModel same = new SameInEveryTabViewModel();

        ActivateItem(new TabViewModel("Tab1", same));
        Items.Add(new TabViewModel("Tab2", same));
        Items.Add(new TabViewModel("Tab3", same));
    }
}

<Window x:Class="CMTest.ShellView"

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

<TabControl x:Name="Items" />

</Window>
public class TabViewModel : Screen

{

    private SameInEveryTabViewModel _same;
    public SameInEveryTabViewModel Same
    {
        get { return _same; }
        set
        {
            _same = value;
            NotifyOfPropertyChange("Same");
        }
    }

    public TabViewModel(string displayName, SameInEveryTabViewModel same)
    {
        DisplayName = displayName;
        this.Same = same;
    }
}

<UserControl x:Class="CMTest.TabView"

         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="auto" />
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>

    <ContentControl x:Name="Same" />

    <TextBlock Grid.Row="1" x:Name="DisplayName" FontSize="30" />

</Grid>

</UserControl>

public class SameInEveryTabViewModel : Screen
{
    public SameInEveryTabViewModel()
    {
        DisplayName = "Same";
    }
}

<UserControl x:Class="CMTest.SameInEveryTabView"

         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid>
    <TextBlock x:Name="DisplayName" />
</Grid> 

</UserControl>


If I would skip with defining SameInEveryTabViewModel in a seperate view and just do it right there in the TabView then it would work fine with a normal old style binding. But of course you would wan't to be able to define it seperatly because SameInEveryTabViewModel might not always be the same.