From ad01c1b614868c3cbc79306aa6a19c9fc06f34a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Camilla=20L=C3=B6wy?= <elmindreda@elmindreda.org>
Date: Thu, 20 Jan 2022 19:21:48 +0100
Subject: [PATCH] Win32: Fix key name code changing global key state

This prevents glfwInit from potentially clobbering the dead key state
for other applications.

Closes #2018
---
 CONTRIBUTORS.md  | 1 +
 README.md        | 2 ++
 src/win32_init.c | 9 +++++++--
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index cb9b0d58..82e91773 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -10,6 +10,7 @@ video tutorials.
  - Matt Arsenault
  - ashishgamedev
  - David Avedissian
+ - Luca Bacci
  - Keith Bauer
  - John Bartholomew
  - Coşku Baş
diff --git a/README.md b/README.md
index 9543919e..0aa309d7 100644
--- a/README.md
+++ b/README.md
@@ -205,6 +205,8 @@ information on what to include when reporting a bug.
  - [Win32] Bugfix: Content scale queries could fail silently (#1615)
  - [Win32] Bugfix: Content scales could have garbage values if monitor was recently
    disconnected (#1615)
+ - [Win32] Bugfix: Key name update modified global key state on Windows 10 1607
+   and later (#2018)
  - [Cocoa] Added support for `VK_EXT_metal_surface` (#1619)
  - [Cocoa] Added locating the Vulkan loader at runtime in an application bundle
  - [Cocoa] Moved main menu creation to GLFW initialization time (#1649)
diff --git a/src/win32_init.c b/src/win32_init.c
index e687d770..0479afe5 100644
--- a/src/win32_init.c
+++ b/src/win32_init.c
@@ -458,6 +458,11 @@ void _glfwUpdateKeyNamesWin32(void)
 {
     int key;
     BYTE state[256] = {0};
+    UINT flags = 0;
+
+    // Avoid modifying the global key state if supported
+    if (_glfwIsWindows10AnniversaryUpdateOrGreaterWin32())
+        flags = (1 << 2);
 
     memset(_glfw.win32.keynames, 0, sizeof(_glfw.win32.keynames));
 
@@ -487,13 +492,13 @@ void _glfwUpdateKeyNamesWin32(void)
 
         length = ToUnicode(vk, scancode, state,
                            chars, sizeof(chars) / sizeof(WCHAR),
-                           0);
+                           flags);
 
         if (length == -1)
         {
             length = ToUnicode(vk, scancode, state,
                                chars, sizeof(chars) / sizeof(WCHAR),
-                               0);
+                               flags);
         }
 
         if (length < 1)