def _task_edit_start(self, task):
pp = Popup(self.top_widget)
pp.part_text_set('title,text', 'Edit task')
en = Entry(pp, editable=True, single_line=True, scrollable=True,
text=task.raw_txt)
en.callback_activated_add(lambda e: self._task_edit_end(task, en, pp))
en.callback_aborted_add(lambda e: pp.delete())
pp.part_content_set('default', en)
b = Button(pp, text='Cancel')
b.callback_clicked_add(lambda b: pp.delete())
pp.part_content_set('button1', b)
b = Button(pp, text='Accept')
b.callback_clicked_add(lambda b: self._task_edit_end(task, en, pp))
pp.part_content_set('button2', b)
pp.show()
en.cursor_begin_set()
en.cursor_selection_begin()
en.cursor_end_set()
en.cursor_selection_end()
