>From 21e4a39eea0da07afd419456a2b6d2df972c622b Mon Sep 17 00:00:00 2001
From: Alan Third <address@hidden>
Date: Thu, 6 Jul 2017 23:10:49 +0100
Subject: [PATCH] Use a run-time check for macOS Sierra tabbing support

* src/nsterm.m (initFrameFromEmacs) [NS_IMPL_COCOA]: Switch from
compile-time check to run-time.
* src/nsterm.h (NSWindowTabbingMode): Define in pre-Sierra macOS.
---
 src/nsterm.h | 8 ++++++++
 src/nsterm.m | 6 +++---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/nsterm.h b/src/nsterm.h
index 0f1b36db7b..da221605b4 100644
--- a/src/nsterm.h
+++ b/src/nsterm.h
@@ -1317,6 +1317,14 @@ extern char gnustep_base_version[];  /* version tracking */
 #ifdef __OBJC__
 typedef NSUInteger NSWindowStyleMask;
 #endif
+
+/* Window tabbing mode enums are new too. */
+enum NSWindowTabbingMode
+  {
+    NSWindowTabbingModeAutomatic,
+    NSWindowTabbingModePreferred,
+    NSWindowTabbingModeDisallowed
+  };
 #endif
 
 #endif	/* HAVE_NS */
diff --git a/src/nsterm.m b/src/nsterm.m
index bf83550b3d..f88b279987 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -7073,9 +7073,9 @@ - (instancetype) initFrameFromEmacs: (struct frame *)f
   /* macOS Sierra automatically enables tabbed windows.  We can't
      allow this to be enabled until it's available on a Free system.
      Currently it only happens by accident and is buggy anyway. */
-#if defined (NS_IMPL_COCOA) && \
-  MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_12
-  [win setTabbingMode: NSWindowTabbingModeDisallowed];
+#ifdef NS_IMPL_COCOA
+  if ([win respondsToSelector: @selector(setTabbingMode:)])
+    [win setTabbingMode: NSWindowTabbingModeDisallowed];
 #endif
 
   ns_window_num++;
-- 
2.12.0