solution.py

#!/usr/bin/env python3
import urwid

palette = [
    ('highlight', '', '', '', 'bold,#ff0', ''),
    ('highlight_focus', '', '', '', 'bold,#ff0', '#da0'),
    ('item_focus','', '', '', '', '#da0'),
]


class Item(urwid.WidgetWrap):
    def __init__(self, number):
        urwid.WidgetWrap.__init__(
            self,
            urwid.AttrMap(
                urwid.Text([
                    str(number),
                    ' before',
                    ('highlight', 'xx'),
                    'after'
                ], align='left')
            ,'item', {'highlight': 'highlight_focus', None: 'item_focus'})
        )

    def selectable(self):
        return True

    def keypress(self, size, key):
        return key


listbox = urwid.ListBox(
    urwid.SimpleListWalker(
        [Item(i) for i in range(10)]
    )
)
loop = urwid.MainLoop(listbox, palette)
loop.screen.set_terminal_properties(colors=256)
loop.run()