SDL: Don't send a mouse leave event if the mouse is outside the window when gaining focus and in relative mode.

SDL Commits
1 
From a70a94e0b3d5c4788535ac7796bc5814095c36d3 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 15 Oct 2021 18:11:19 -0700
Subject: [PATCH] Don't send a mouse leave event if the mouse is outside the
 window when gaining focus and in relative mode.

---
 src/video/windows/SDL_windowsevents.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/video/windows/SDL_windowsevents.c b/src/video/windows/SDL_windowsevents.c
index 3a41e1421e..d30642a1be 100644
--- a/src/video/windows/SDL_windowsevents.c
+++ b/src/video/windows/SDL_windowsevents.c
@@ -403,9 +403,12 @@ WIN_UpdateFocus(SDL_Window *window)
 
         SDL_SetKeyboardFocus(window);
 
-        GetCursorPos(&cursorPos);
-        ScreenToClient(hwnd, &cursorPos);
-        SDL_SendMouseMotion(window, 0, 0, cursorPos.x, cursorPos.y);
+        /* In relative mode we are guaranteed to have mouse focus if we have keyboard focus */
+        if (!SDL_GetMouse()->relative_mode) {
+            GetCursorPos(&cursorPos);
+            ScreenToClient(hwnd, &cursorPos);
+            SDL_SendMouseMotion(window, 0, 0, cursorPos.x, cursorPos.y);
+        }
 
         WIN_CheckAsyncMouseRelease(data);
         WIN_UpdateClipCursor(window);