use env_logger in all examples (#2934)

examples/user_attention/Cargo.toml

@@ -8,4 +8,7 @@ rust-version = "1.65"
 publish = false
 
 [dependencies]
-eframe = { path = "../../crates/eframe" }
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a screenshot using EFRAME_SCREENSHOT_TO
+] }
+env_logger = "0.10"

examples/user_attention/src/main.rs

@@ -1,8 +1,23 @@
-use eframe::egui::{Button, CentralPanel, Context, UserAttentionType};
-use eframe::{CreationContext, NativeOptions};
+use eframe::{
+    egui::{Button, CentralPanel, Context, UserAttentionType},
+    CreationContext, NativeOptions,
+};
 
 use std::time::{Duration, SystemTime};
 
+fn main() -> eframe::Result<()> {
+    env_logger::init(); // Log to stderr (if you run with `RUST_LOG=debug`).
+    let native_options = NativeOptions {
+        initial_window_size: Some(eframe::egui::vec2(400., 200.)),
+        ..Default::default()
+    };
+    eframe::run_native(
+        "User attention test",
+        native_options,
+        Box::new(|cc| Box::new(Application::new(cc))),
+    )
+}
+
 fn repr(attention: UserAttentionType) -> String {
     format!("{:?}", attention)
 }
@@ -116,15 +131,3 @@ impl eframe::App for Application {
         ctx.request_repaint_after(Self::repaint_max_timeout());
     }
 }
-
-fn main() -> eframe::Result<()> {
-    let native_options = NativeOptions {
-        initial_window_size: Some(eframe::egui::vec2(400., 200.)),
-        ..Default::default()
-    };
-    eframe::run_native(
-        "User attention test",
-        native_options,
-        Box::new(|cc| Box::new(Application::new(cc))),
-    )
-}