Double mouse device events with confined cursor

Description

When confining the cursor to a window all DeviceEvents from that mouse are doubled (note: not a duplicate of #2332, as the accepted fix is already implemented in the winit version im using. Behavior is very similar though).

Here is some code to reproduce:

use std::{
	thread,
	time::Duration
};
use winit::{
	event::{
		Event,
		WindowEvent,
		DeviceEvent
	},
	event_loop::{
		EventLoop,
		ControlFlow
	},
	keyboard::{KeyCode, PhysicalKey},
	window::{CursorGrabMode, WindowAttributes}
};

fn main() {
	let event_loop = EventLoop::new().unwrap();
	let window = event_loop.create_window(WindowAttributes::default()).unwrap();
	thread::sleep(Duration::from_millis(50));
	
	
	window.set_cursor_grab(CursorGrabMode::Confined).unwrap();
	
	
	event_loop.run(move |event, event_loop| {
		event_loop.set_control_flow(ControlFlow::Poll);
		match event {
			Event::DeviceEvent {event, ..} => {
				match event {
					DeviceEvent::Key(e) => {
						if e.physical_key == PhysicalKey::Code(KeyCode::Escape) {
							event_loop.exit();
						}
					}
					DeviceEvent::Button { button, state } => {
						println!("mouse button {} was {:?}", button, state);
					},
					DeviceEvent::MouseWheel {delta} => {
						//println!("delta: {:?}", delta);
					},
					DeviceEvent::MouseMotion {delta} => {
						//println!("move_delta: {:?}", delta);
					}
					_ => {}
				}
			}
			Event::WindowEvent { event, .. } => match event {
				WindowEvent::CloseRequested => {
					event_loop.exit();
				}
				_ => (),
			},
			_ => (),
		}
	}).unwrap();
}

OS and window mananger

Ubuntu with GNOME Shell

Winit version

0.30.3

Run the provided Rust reproducer with winit 0.30.3 on Ubuntu with GNOME Shell, focusing on CursorGrabMode::Confined and the DeviceEvent handlers. Trace the relevant confined-cursor event path and compare button, wheel, and motion counts. Done means each physical mouse event is delivered once rather than doubled.