Styling of Value templates

Hi all,

I'm currently playing with the PropertyGrid look and want to put curved borders around the value (and possibly name) fields but am unable to work out which template to edit. We've got the templates and style xaml for our registered products (PropertyGrid and editors) and I've tried adding a Border element around the control template content of the TreeListViewCell and the TreeListViewItem but to no avail.

Any pointers as to what I should be editing?

Thanks

Rick