Send the event before waking up the message pump. (#3418)

CHANGELOG.md

@@ -12,6 +12,7 @@ Unreleased` header.
 # Unreleased
 
 - On macOS, fix incorrect IME cursor rect origin.
+- On Windows, fixed a race condition when sending an event through the loop proxy.
 
 # 0.29.10
 

src/platform_impl/windows/event_loop.rs

@@ -696,14 +696,13 @@ impl<T: 'static> Clone for EventLoopProxy<T> {
 
 impl<T: 'static> EventLoopProxy<T> {
     pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        unsafe {
+        self.event_send
-            if PostMessageW(self.target_window, USER_EVENT_MSG_ID.get(), 0, 0) != false.into() {
+            .send(event)
-                self.event_send.send(event).ok();
+            .map(|result| {
-                Ok(())
+                unsafe { PostMessageW(self.target_window, USER_EVENT_MSG_ID.get(), 0, 0) };
-            } else {
+                result
-                Err(EventLoopClosed(event))
+            })
-            }
+            .map_err(|e| EventLoopClosed(e.0))
-        }
     }
 }