How to dynamically bind parent element

I'm dynamically creating multiple expandable panel in silverlight. Every panel con开发者_如何学Pythontains textbox. I need to bind this textbox to parent expandable panel header property.

How to do it dynamically?

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<Textbox.Text="{Binding Path=Header RelativeSource={RelativeSource Mode="FindAncestor" AncestorType="{x:Type ExpandablePanel}}}"/>