Context Menu Binding to Parent Window's Datacontext

Question

I have a TreeListControl that binds to a collection in my VM. I also want to define the context menu inside the treelistcontrol having its header text bind to another string

Answer 1

Provide a name for your window and explicitly bind to it such as

<window  x:Name="ReportsPage"/>

...

 <MenuItem DataContext="{Binding ElementName=ReportsPage}"/>

---

UPDATE

Since the context menu is actually in its own window, binding is a bit trickier. Hence the best bet is to walk up the RelativeSource to the context's parent and pull the header text from there:

    <Window.DataContext>
        <local:MainVM HeaderText="Jabberwocky" />
    </Window.DataContext>

    ...

<TextBlock Text="{Binding HeaderText}">
    <TextBlock.ContextMenu>
        <ContextMenu>

<MenuItem Header="{Binding Path=Parent.DataContext.HeaderText, 
                    RelativeSource={RelativeSource Self}}" />

        </ContextMenu>
    </TextBlock.ContextMenu>

Which for this context produces this

Answer 2

This binds to a Window:

DataContext="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}}"

If the command AddItemCommand and property AddItemText are defined on the Window ViewModel, bind to Window DataContext:

DataContext="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=DataContext}"