Gtk-rs create thread in button click event

help
1

hello,
i want to write an app to get some data from internet, this operate will take a long time, so i want to fetch data on a thread. when get finished, put data into text box.

struct App {
    btn: gtk::Button,
    text: gtk::Entry,
}

impl App {
    fn get_data(&mut self) {
           // work
           thread::spawn(move || {
                // fetch data from internet, it takes a long time
                // TODO: put data into self.Entry
           });
    }
}

....

fn gui_main() {
    ... // construct items
    let app = Rc::new(RefCell::new(App{....}); // init
    let a = app.clone();
    // connect event
    btn.connect_clicked(move |_| {App::get_data(a.deref().borrow_mut().deref_mut());});
}

and i dont know how to put data into my gtk::Entry, can any body give me a example code ? please.