SDL: cocoa: Fix 1px border in fullscreen on Tahoe (48e5f)

SDL Commits
1 
From 48e5fc7b69b8eaccbdcbc3c4f7a33ea52083cf68 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <[EMAIL REDACTED]>
Date: Sat, 7 Feb 2026 23:57:24 -0600
Subject: [PATCH] cocoa: Fix 1px border in fullscreen on Tahoe

(cherry picked from commit 1d83a35e48a6fe056c8348752cd91d2ed403e536)
---
 src/video/cocoa/SDL_cocoawindow.m | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/video/cocoa/SDL_cocoawindow.m b/src/video/cocoa/SDL_cocoawindow.m
index 1f7404d3104ba..277aa885b9ecd 100644
--- a/src/video/cocoa/SDL_cocoawindow.m
+++ b/src/video/cocoa/SDL_cocoawindow.m
@@ -3054,6 +3054,9 @@ SDL_FullscreenResult Cocoa_SetWindowFullscreen(SDL_VideoDevice *_this, SDL_Windo
         [nswindow setContentSize:rect.size];
         [nswindow setFrameOrigin:rect.origin];
 
+        // Disable the window shadow in fullscreen to avoid a visible 1px border on Tahoe
+        nswindow.hasShadow = !fullscreen && !(window->flags & SDL_WINDOW_TRANSPARENT);
+
         // When the window style changes the title is cleared
         if (!fullscreen) {
             Cocoa_SetWindowTitle(_this, window);