From 539f4bdca28ba959dd631dd2e90fded528cfc942 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Camilla=20L=C3=B6wy?= <elmindreda@elmindreda.org>
Date: Wed, 8 Jul 2020 15:53:01 +0200
Subject: [PATCH] X11: Fix race in window hovered query

The window decoration window can go away between calls to XQueryPointer,
for example if the GLFW_DECORATED window attribute was just cleared.

(cherry picked from commit ceb20c7f97994106db17cc66bd8abad331bc355e)
---
 src/x11_window.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/x11_window.c b/src/x11_window.c
index 9df28973..9ffb5e9e 100644
--- a/src/x11_window.c
+++ b/src/x11_window.c
@@ -2591,11 +2591,19 @@ int _glfwPlatformWindowHovered(_GLFWwindow* window)
         int rootX, rootY, childX, childY;
         unsigned int mask;
 
-        if (!XQueryPointer(_glfw.x11.display, w,
-                           &root, &w, &rootX, &rootY, &childX, &childY, &mask))
-        {
+        _glfwGrabErrorHandlerX11();
+
+        const Bool result = XQueryPointer(_glfw.x11.display, w,
+                                          &root, &w, &rootX, &rootY,
+                                          &childX, &childY, &mask);
+
+        _glfwReleaseErrorHandlerX11();
+
+        if (_glfw.x11.errorCode == BadWindow)
+            w = _glfw.x11.root;
+
+        if (!result)
             return GLFW_FALSE;
-        }
 
         if (w == window->x11.handle)
             return GLFW_TRUE;