Fix XSendEvent crash & bootsplash.

Fixes a crash due to an Xlib error, as well as ensures that Godot
holds the correct size of the window after window modes have been
applied, before exiting the DisplayServerX11 constructor. This ensures
the bootsplash will be displayed with the correct dimensions.

Fixes #65320

platform/linuxbsd/display_server_x11.cpp

@@ -4900,6 +4900,8 @@ DisplayServerX11::DisplayServerX11(const String &p_rendering_driver, WindowMode
 		}
 	}
 	show_window(main_window);
+	XSync(x11_display, False);
+	_validate_mode_on_map(main_window);
 
 #if defined(VULKAN_ENABLED)
 	if (rendering_driver == "vulkan") {
@@ -5046,24 +5048,13 @@ DisplayServerX11::DisplayServerX11(const String &p_rendering_driver, WindowMode
 	}
 	cursor_set_shape(CURSOR_BUSY);
 
-	Vector<XEvent> save_events;
-	while (XPending(x11_display) > 0) {
-		XEvent xevent{ 0 };
-		XNextEvent(x11_display, &xevent);
-		if (xevent.type == ConfigureNotify) {
-			_window_changed(&xevent);
-		} else {
-			// Don't discard this event, we must resend it...
-			save_events.push_back(xevent);
-		}
-	}
-
-	// Resend events that would have been dropped by the early event queue
-	// processing we just performed.
-	for (XEvent &ev : save_events) {
-		XSendEvent(x11_display, ev.xany.window, False, 0, &ev);
+	// Search the X11 event queue for ConfigureNotify events and process all
+	// that are currently queued early, so we can get the final window size
+	// for correctly drawing of the bootsplash.
+	XEvent config_event;
+	while (XCheckTypedEvent(x11_display, ConfigureNotify, &config_event)) {
+		_window_changed(&config_event);
 	}
-
 	events_thread.start(_poll_events_thread, this);
 
 	_update_real_mouse_position(windows[MAIN_WINDOW_ID]);