SDL: Fixed missing line

From c824060503c3075dcb38cf882b10eaf9fa154209 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Mon, 27 Feb 2023 21:08:50 -0800
Subject: [PATCH] Fixed missing line

---
 src/video/SDL_video.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/video/SDL_video.c b/src/video/SDL_video.c
index 6b8c5eb85ffa..0d9aaa322279 100644
--- a/src/video/SDL_video.c
+++ b/src/video/SDL_video.c
@@ -1374,6 +1374,7 @@ static int SDL_UpdateFullscreenMode(SDL_Window *window, SDL_bool fullscreen)
                     if (_this->SetWindowFullscreen) {
                         _this->SetWindowFullscreen(_this, window, last_display, SDL_FALSE);
                     }
+                    last_display->fullscreen_window = NULL;
                 }
             }
         }