SDL: Don't warp the mouse for relative mode when the window doesn't have focus

SDL Commits
1 
From b28ed02803263fb2bd0b3c9631f6dc4c1f47d8ba Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 13 Aug 2021 11:39:41 -0700
Subject: [PATCH] Don't warp the mouse for relative mode when the window
 doesn't have focus

---
 src/events/SDL_mouse.c                | 4 +++-
 src/video/windows/SDL_windowsevents.c | 3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/events/SDL_mouse.c b/src/events/SDL_mouse.c
index a776bcca81..184942e2f1 100644
--- a/src/events/SDL_mouse.c
+++ b/src/events/SDL_mouse.c
@@ -358,7 +358,9 @@ SDL_PrivateSendMouseMotion(SDL_Window * window, SDL_MouseID mouseID, int relativ
             mouse->last_y = center_y;
             return 0;
         }
-        SDL_WarpMouseInWindow(window, center_x, center_y);
+        if (window && (window->flags & SDL_WINDOW_INPUT_FOCUS) != 0) {
+            SDL_WarpMouseInWindow(window, center_x, center_y);
+        }
     }
 
     if (relative) {
diff --git a/src/video/windows/SDL_windowsevents.c b/src/video/windows/SDL_windowsevents.c
index 3fbd5a862d..426024a586 100644
--- a/src/video/windows/SDL_windowsevents.c
+++ b/src/video/windows/SDL_windowsevents.c
@@ -663,7 +663,8 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
                 if (GetMouseMessageSource() != SDL_MOUSE_EVENT_SOURCE_TOUCH &&
                     lParam != data->last_pointer_update) {
                     SDL_SendMouseMotion(data->window, 0, 0, GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
-                    if (isWin10FCUorNewer && mouse->relative_mode_warp) {
+                    if (isWin10FCUorNewer && mouse->relative_mode_warp &&
+                        (data->window->flags & SDL_WINDOW_INPUT_FOCUS)) {
                         /* To work around #3931, Win10 bug introduced in Fall Creators Update, where
                            SetCursorPos() (SDL_WarpMouseInWindow()) doesn't reliably generate mouse events anymore,
                            after each windows mouse event generate a fake event for the middle of the window