Web: account for canvas being focused already (#3369)

src/platform_impl/web/event_loop/window_target.rs

@@ -5,6 +5,8 @@ use std::iter;
 use std::marker::PhantomData;
 use std::rc::{Rc, Weak};
 
+use web_sys::Element;
+
 use super::runner::{EventWrapper, Execution};
 use super::{
  super::{monitor::MonitorHandle, KeyEventExtra},
@@ -118,6 +120,25 @@ impl<T> EventLoopWindowTarget<T> {
  }
  });
 
+ // It is possible that at this point the canvas has
+ // been focused before the callback can be called.
+ let focused = canvas
+ .document()
+ .active_element()
+ .filter(|element| {
+ let canvas: &Element = canvas.raw();
+ element == canvas
+ })
+ .is_some();
+
+ if focused {
+ canvas.has_focus.set(true);
+ self.runner.send_event(Event::WindowEvent {
+ window_id: RootWindowId(id),
+ event: WindowEvent::Focused(true),
+ })
+ }
+
  let runner = self.runner.clone();
  let modifiers = self.modifiers.clone();
  canvas.on_keyboard_press(