egui/egui_demo_app/src/main.rs

// Forbid warnings in release builds:
#![cfg_attr(not(debug_assertions), deny(warnings))]
#![forbid(unsafe_code)]
#![warn(clippy::all, rust_2018_idioms)]

// When compiling natively:
fn main() {
    let app = egui_demo_lib::WrapApp::default();
    let options = eframe::NativeOptions {
        // Let's show off that we support transparent windows
        transparent: true,
        drag_and_drop_support: true,
        ..Default::default()
    };
    eframe::run_native(Box::new(app), options);
}