Retry requesting input focus until the window is focused at startup

src/renderer.rs

@@ -1,6 +1,7 @@
 use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
 use std::sync::mpsc::Receiver;
 use std::sync::{Arc, Condvar, Mutex};
+use std::time::{Duration, Instant};
 
 use bytemuck::{Pod, Zeroable};
 use pyo3::prelude::*;
@@ -79,7 +80,14 @@ pub fn start(
         w.set_close_polling(true);
         w.set_key_polling(true);
         w.set_char_polling(true);
+        w.set_focus_polling(true);
         w.focus();
+        let focus_deadline = Instant::now() + Duration::from_secs(2);
+        while Instant::now() < focus_deadline && !w.is_focused() {
+            glfw_ctx.poll_events();
+            w.focus();
+            std::thread::sleep(Duration::from_millis(10));
+        }
         let fb = w.get_framebuffer_size();
         fb_w = fb.0.max(1) as u32;
         fb_h = fb.1.max(1) as u32;