struct App<'a> {
    username_state: TextState<'a>,
    password_state: TextState<'a>,
    invisible_state: TextState<'a>,
}

impl<'a> App<'a> {
    fn draw_ui<B: Backend>(&mut self, frame: &mut Frame<B>) {
        let (username_area, password_area, invisible_area) = split_layout(frame.size())

        TextPrompt::from("Username")
            .draw(frame, username_area, &mut self.username_state);

        TextPrompt::from("Password")
            .with_render_style(TextRenderStyle::Password)
            .draw(frame, password_area, &mut self.password_state);

        TextPrompt::from("Invisible")
            .with_render_style(TextRenderStyle::Invisible)
            .draw(frame, invisible_area, &mut self.invisible_state);
    }
}