How can I track which element of ItemsControl caused ContexMenu to open? - wpf

Question

In my book editor app I need to display themes and subthemes in an hierarchical order, so I made such an markup:
<StackPanel>
<ScrollViewer>
<Grid ColumnDefinitions="auto, *" RowDefinitions="auto">
<ItemsControl Grid.Column="0" Grid.Row="0" Items="{Binding Book.Themes}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel>
<Button Content="{Binding Name}" Command="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}, Path=DataContext.UpdateSubthemesVisibilityCommand}" CommandParameter="{Binding Name}"/>
<ItemsControl Items="{Binding Subthemes}" IsVisible="{Binding AreSubthemesVisible}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Content="{Binding Name}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ContextMenu>
<ContextMenu>
<MenuItem Header="Rename" />
<MenuItem Header="Delete"/>
</ContextMenu>
</ItemsControl.ContextMenu>
</ItemsControl>
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ContextMenu>
<ContextMenu>
<MenuItem Header="Rename" Command="{Binding RenameThemeCommand}" CommandParameter="...How to bind it to button which cause menu to open"/>
<MenuItem Header="Delete"/>
</ContextMenu>
</ItemsControl.ContextMenu>
</ItemsControl>
</Grid>
</ScrollViewer>
</StackPanel>
Maybe markup isn't quite clear, but the point is that I have external ItemsControl and internal one. External one's items have structure: button (theme name) + internal ItemsControl which presents subthemes' names as buttons too. Here is Screenshot:
Each ItemsControl has its own ContextMenu, but I can't bind them properly. I want "Rename" MenuItems to be bind to Button.Content of Button which right click caused menu to open. How should I do this here?
I am using MVVM Avalonia, but I hope in WPF it's working the same way so that I could add WPF hashtag to this question.

Answer 1

You don't need to add ContextMenu to ItemsControl. It needs to be added to the items ItemsControl.
This is done in ItemContainerStyle.
In such a case, in ContextMenu DataContext will contain the element on which the ContextMenu is called.
Example:
<Window.Resources>
<spec:StringCollection x:Key="strings">
<sys:String>First</sys:String>
<sys:String>Second</sys:String>
<sys:String>Third</sys:String>
</spec:StringCollection>
<Style x:Key="ItemStyle" TargetType="ContentPresenter">
<Setter Property="ContextMenu">
<Setter.Value>
<ContextMenu>
<TextBlock Text="{Binding}"/>
</ContextMenu>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<ItemsControl ItemsSource="{StaticResource strings}"
ItemContainerStyle="{StaticResource ItemStyle}"/>