Q:

SelectedItem unknown DataContext although datacontext is set

I have a ListBox with a static ObservableCollection<HUDInfo> is bound.  The DataTrigger shows the following error "PropertyPath | Cannot resolve property 'StatusConnection' in data context of type 'my window class'". 
                    <ListBox 
                        x:Name="ListBoxAvailableHuDs" 
                        ItemsSource="{Binding AvailableHUDs, Source={x:Static Core:HudModel. Current}}"
                        <ListBox. ItemContainerStyle>
                            <Style TargetType="ListBoxItem">
                                <Style. Triggers>
                                    <DataTrigger Binding="{Binding StatusConnection}" Value="CanDisconnect">
                                        <Setter Property="FontWeight" Value="Bold"/>
                                    </DataTrigger>
                                </Style. Triggers>
                            </Style>
                        </ListBox. ItemContainerStyle>
                    </ListBox>

On the Window I set the following DataContext:
DataContext="{Binding RelativeSource={RelativeSource Self}}"
My TextBlock also can not resolve the DataContext
                    <TextBlock 
                        Text="{Binding SelectedItem. DeviceId, ElementName=ListBoxAvailableHuDs}"/>

"Cannot resolve property 'DeviceId' in data context of type 'object'"
How to set the DataContext of the ListBox to HudInfo or that the ListBoxItem is using the right DataContext? 

A:

At runtime the data context is resolved correctly for each list box item, however, the designer is not able to do this.   You may be able to do the following:
<Style TargetType="ListBoxItem" d:DataContext="{d:DesignInstance HudInfo }">
    <Style. Triggers>
    ...
    </Style. Triggers>
</Style TargetType="ListBoxItem" d:DataContext="{d:DesignInstance HudInfo">

with 
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

I find this can cause an error to be shown in the designer - underlining the d:DataContext part, but it at least allows it to resolve the bindings.