You should try to put the ContextMenu in your ListItemTemplate
<Application.Resources>
<DataTemplate x:Key="ListItemTemplate">
<StackPanel>
<toolkit:ContextMenuService.ContextMenu>
<toolkit:ContextMenu>
<toolkit:MenuItem x:Name="DoneMenuItem"
Header="Done"
Command="{Binding Main.DoneCommand, Source={StaticResource Locator}}"
CommandParameter="{Binding}"/>
</toolkit:ContextMenu>
</toolkit:ContextMenuService.ContextMenu>
<TextBlock Text="{Binding Title}" />
</StackPanel>
</DataTemplate>
And you can remove your ListBox.ItemContainerStyle tag