The listbox isn't part of the themed ttk widgets. The ttk::treview is,
and that can be set up as a single-column list display. There may be an
example of how to do this in the docs or source code tree (I don't use
the widget myself so I don't have any sample code to share).
--Kevin
--
Kevin Walzer
Code by Kevin
http://www.codebykevin.com