How to edit a ListBox Item

I have a simple listbox of file names.   I have a button that I want to rename a file listed in the listbox.  

I have modified the default ListBoxItemStyle template and added a TextBox and made the visibility Collapsed.

<Grid><Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true"><ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/></Border><TextBox Name="EditableText" Visibility="Collapsed"/></Grid>

When I press my button I want to be able to edit the text of the selected ListBox item.  When you press enter on the textbox I want the item to be changed.

I was thinking I could use the Tag property of the ListBoxItem and set it to true to show the textbox but I can't figure out how to do that or how to hide the textbox when the textbox has lost focus.

Any help?

Jeff Davis