Question

I have TreeView which contains different item types. Item Styles are defined over a custom ItemContainerStyleSelector property.

My styles are all sharing a base style and only item specific stuff is defined in each style. It looks like this:

<Style x:Key="BaseStyle" TargetType="{x:Type TreeViewItem}">
...
</Style>

<Style x:Key ="SomeSpecificStyle" TargetType="{x:Type TreeViewItem}" BasedOn="{StaticResource BaseStyle}">
   <Setter Property="ContextMenu" Value="{StaticResource NodeContextMenu}"/>
   ...  
</Style>

<Style x:Key ="SomeSpecificStyle" TargetType="{x:Type TreeViewItem}" BasedOn="{StaticResource BaseStyle}">
   <Setter Property="ContextMenu" Value="{StaticResource AnotherNodeContextMenu}"/>
   ...  
</Style>

The context menu is defined like this

<ContextMenu x:Key="NodeContextMenu">
  <MenuItem Header="Select Views" Command="{Binding Path=OpenViewsCommand}" />
  ...other specific entries
  <MenuItem Header="Remove" Command="{Binding Path=DocumentRemoveCommand}" />
  ...other entries common for all menus
</ContextMenu>

Another context menu also should contain those common items like remove. These need to be replicated by copy paste every time the command properties, etc are changing. A hell for maintainability. Is there a way to define a context menu which contains the common items, and then “derive” specific context menus?

Edit: I found a solution with the hints from this thread:
I define a Collection with the common items, and use a composite collection when defining a menu to include both new items and the common items collection

<CompositeCollection x:Key="CommonItems"> 
  <MenuItem Header="Remove" Command="{Binding Path=DocumentRemoveCommand}">
  ....Other common stuff
</CompositeCollection>

<ContextMenu x:Key="NodeContextMenu">
  <ContextMenu.ItemsSource>
    <CompositeCollection>
      <MenuItem Header="Select Views" Command="{Binding Path=OpenViewsCommand}" />
      <CollectionContainer Collection="{StaticResource CommonItems}" />
    </CompositeCollection>
  </ContextMenu.ItemsSource>
</ContextMenu>

Answer 1

You can declare the items as resource and reference them:

<Some.Resources>
    <MenuItem x:Key="mi_SelectViews" x:Shared="false"
              Header="Select Views" Command="{Binding Path=OpenViewsCommand}" />
    <MenuItem x:Key="mi_Remove" x:Shared="false"
              Header="Remove" Command="{Binding Path=DocumentRemoveCommand}" />
</Some.Resources>

<ContextMenu x:Key="NodeContextMenu">
  <StaticResource ResourceKey="mi_SelectViews" />
  ...other specific entries
  <StaticResource ResourceKey="mi_Remove" />
  ...other entries common for all menus
</ContextMenu>

(The x:Shared is important)

---

Another possibility would be to generate MenuItems via a object model approach, you just bind the ItemsSource to some list of objects which model the functionality of a MenuItem (i.e. properties for child items, header and command), then you can create one Remove model which can be part of multiple lists.