fltk 0.9.3

use fltk::{app::*, frame::*, window::*};

#[derive(Debug, Copy, Clone)]
pub enum Message {
    Increment(i32),
    Decrement(i32),
}

fn inc_frame(frame: &mut Frame, val: &mut i32, step: i32) {
    *val += step;
    frame.set_label(&val.to_string());
}

fn main() {
    let app = App::default();
    let mut wind = Window::new(100, 100, 400, 300, "Hello from rust");
    let mut frame = Frame::new(0, 0, 400, 300, "");

    let mut val = 0;

    wind.show();

    let (s, r) = channel::<Message>();

    std::thread::spawn(move || loop {
        std::thread::sleep(std::time::Duration::from_millis(1000));
        s.send(Message::Increment(2));
    });

    while app.wait().unwrap() {
        if let Some(msg) = r.recv() {
            if let Message::Increment(step) = msg {
                inc_frame(&mut frame, &mut val, step)
            }
        }
    }
}