Ridiculous simple calculator in GTK-RS

Cargo.toml

[package]
name = "ridiculous_calculator"
version = "0.1.0"
authors = ["Laurent Bernabe <[email protected]>"]
license = "MIT"

[dependencies]
[dependencies.gtk]
version = "0.5.0"

main.rs

extern crate gtk;

use gtk::prelude::*;

use gtk::{Window, WindowType};
use gtk::{Box, Orientation};
use gtk::{ComboBoxText};
use gtk::{Button};

fn main() {
    if gtk::init().is_err() {
        println!("Failed to intialize GTK !");
        return;
    }

    let left_operand_values = ComboBoxText::new();
    let right_operand_values = ComboBoxText::new();
    let operator_values = ComboBoxText::new();

    let operands_possibilities = [
        "2", "3", "4", "5", "6", "7", "8", "9"
    ];

    let operators_possibilities = [
        "+", "-", "*"
    ];

    for elem in operands_possibilities.iter() {
        left_operand_values.append_text(elem);
        right_operand_values.append_text(elem);
    }

    for elem in operators_possibilities.iter() {
        operator_values.append_text(elem);
    }

    left_operand_values.set_active(0);
    right_operand_values.set_active(0);
    operator_values.set_active(0);

    let validate_button = Button::new_with_label("Validate");

    let combo_boxes_box = Box::new(Orientation::Horizontal, 10);
    combo_boxes_box.pack_start(&left_operand_values, true, false, 10);
    combo_boxes_box.pack_start(&operator_values, true, false, 10);
    combo_boxes_box.pack_start(&right_operand_values, true, false, 10);

    let button_box = Box::new(Orientation::Horizontal, 10);
    button_box.pack_start(&validate_button, true, false, 10);

    let main_vertical_box = Box::new(Orientation::Vertical, 3);
    main_vertical_box.pack_start(&combo_boxes_box, true, false, 3);
    main_vertical_box.pack_start(&button_box, true, false, 3);

    let window = Window::new(WindowType::Toplevel);
    window.set_title("Simple ridiculous calculator");
    window.set_default_size(480, 220);

    window.connect_delete_event(|_, _| {
        gtk::main_quit();
        Inhibit(false)
    });

    window.add(&main_vertical_box);
    window.show_all();

    gtk::main();
}

First version : not interactive at all (revision 1)