'When title/format change, invalidate Preset in E-book options tab'

def settings_changed(self):

    cf = unicode(self.format.currentText()).lower()
    if ((cf in ['azw3', 'epub', 'mobi']) and hasattr(self.tabs.widget(1), 'settings_changed')):
        self.tabs.widget(1).settings_changed('title/format')
