How do I add static items to a context menu that binds to an existing data source?

Question

I have a context menu that binds to a collection using ItemsSource:

<Button Content="Submit">
<Button.ContextMenu>
    <ContextMenu Name="SubmitButtonContextMenu" ItemsSource="{Binding MyDataSource}">
        <ContextMenu.ItemContainerStyle>
            <Style TargetType="{x:Type MenuItem}">
                <!-- Setters -->
            </Style>
        </ContextMenu.ItemContainerStyle>
    </ContextMenu>
</Button.ContextMenu>
</Button>

And it currently would show up like this: Menu Item

Basically, I want to add two static items: another MenuItem that will never change, and a spacer to separate my static content and my dynamic content. I could just stuff my collection that it's being bound to with this data, but I feel like there should be a more elegant solution. I would also prefer to avoid using subcontext menus.

EDIT: Here's what I ended up implementing:

<Window ...>
<Window.Resources>
    <s:SubmitItemStyleSelector x:Key="SubmitItemStyleSelector">
        <s:SubmitItemStyleSelector.SubmitButtonStyle>
            <Style TargetType="MenuItem">
                <!--Setters-->
            </Style>
        </s:SubmitItemStyleSelector.SubmitButtonStyle>
    </s:SubmitItemStyleSelector>
    <CollectionViewSource x:Key="MyDataViewSource" Source="{Binding MyDataSource}"/>
</Window.Resources>
...
<Button Content="Submit">
    <Button.ContextMenu>
        <ContextMenu ItemContainerStyleSelector="{Binding Source={StaticResource SubmitItemStyleSelector}}">
            <ContextMenu.ItemsSource>
                <CompositeCollection>
                    <MenuItem Header="No Change"/>
                    <Separator/>
                    <CollectionContainer Collection="{Binding Source={StaticResource MyDataViewSource}}"/>
                </CompositeCollection>
            </ContextMenu.ItemsSource>
        </ContextMenu>
    </Button.ContextMenu>
</Button>

And then my SubmitItemStyleSelector finds the types I want from MyDataSource to do additional styling on just those items.

Answer 1

You should use CompositeCollection (msdn) :

<Window ..
       >
    <Window.Resources>
        <CollectionViewSource x:Key="MyDynamicDataSource" Source="{Binding Path=MyDataSource}" />
    ...
    </Window.Resources>
    ...
    <Button Content="Submit" >
        <Button.ContextMenu>
            <ContextMenu Name="SubmitButtonContextMenu">
                <ContextMenu.ItemsSource>
                    <CompositeCollection>
                        <MenuItem Header="First static item" />
                        <MenuItem Header="Second static item" />
                        <Separator />
                        <CollectionContainer Collection="{Binding Source={StaticResource MyDynamicDataSource}}" />
                    </CompositeCollection>
                </ContextMenu.ItemsSource>
            </ContextMenu>
        </Button.ContextMenu>
    </Button>
    ...
</Window>