master f7d98db: Revert "src/nsterm.m: fix window tabbing on macOS"

[Alan Third]

branch: master
commit f7d98dbba0dc7c7e9fea63d39fe88aefa4e9f66c
Author: Alan Third <alan@idiocy.org>
Commit: Alan Third <alan@idiocy.org>

    Revert "src/nsterm.m: fix window tabbing on macOS"
    
    This reverts commit 2207f9adccc0411b7ad73a3703f16250d7f8e139.
---
 etc/NEWS     | 8 --------
 src/nsterm.m | 8 ++++++++
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 64b39d7..eadf3e7 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -3235,14 +3235,6 @@ The new variable 'xwidget-webkit-download-dir' says 
where to download to.
 ".so" suffix is supported as well.
 
 +++
-** On macOS, Emacs now supports native tabs (in macOS 10.12 and later).
-Native tabbing behavior is specified system-wide via System
-Preferences, under under "General => Prefer tabs when opening
-documents".  In macOS versions 10.15 and earlier, this option is
-located under Dock instead.  Note that this feature is unrelated to
-the Emacs 'tab-bar-mode'.
-
-+++
 ** On MS-Windows, Emacs can now toggle the IME.
 A new function 'w32-set-ime-open-status' can now be used to disable
 and enable the MS-Windows native Input Method Editor (IME) at run
diff --git a/src/nsterm.m b/src/nsterm.m
index 11b02f1..f616824 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -7628,6 +7628,14 @@ not_in_argv (NSString *arg)
          selector:@selector (viewDidResize:)
              name:NSViewFrameDidChangeNotification object:nil];
 
+  /* 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.  */
+#ifdef NS_IMPL_COCOA
+  if ([win respondsToSelector: @selector(setTabbingMode:)])
+    [win setTabbingMode: NSWindowTabbingModeDisallowed];
+#endif
+
   ns_window_num++;
   return self;
 }