#11756 Respect system preferences for tabbing on Mac

src/LyXRC.cpp

@@ -46,6 +46,10 @@
 #include "support/TempFile.h"
 #include "support/userinfo.h"
 
+#ifdef USE_MACOSX_PACKAGING
+#include "support/AppleSupport.h"
+#endif
+
 #include <fstream>
 #include <iostream>
 #include <algorithm>
@@ -286,6 +290,10 @@ LyXRC::ReturnValues LyXRC::read(Lexer & lexrc, bool check_format)
 	// format prior to 2.0 and introduction of format tag
 	unsigned int rc_format = 0;
 
+#ifdef USE_MACOSX_PACKAGING
+	open_buffers_in_tabs = appleUserTabbingPreferenceAlways();
+#endif
+
 	while (lexrc.isOK()) {
 		// By using two switches we take advantage of the compiler
 		// telling us if we have missed a LyXRCTags element in

src/support/AppleSupport.h

@@ -17,6 +17,9 @@ extern "C" {
 #endif
 	void appleCleanupEditMenu();
 	void appleCleanupViewMenu();
+
+	// query the system preferences for users tabbing preference
+	bool appleUserTabbingPreferenceAlways();
 #ifdef __cplusplus
 }
 #endif

src/support/AppleSupport.m

@@ -24,12 +24,21 @@ void appleCleanupEditMenu() {
 
 void appleCleanupViewMenu() {
 
-#ifdef AVAILABLE_MAC_OS_X_VERSION_10_12_AND_LATER
 	// Remove the "Show Tab Bar" menu item from the "View" menu, if supported
+	// See the Apple developer release notes:
+	// What should an application which already has support for tabbing do?
+	// - The application should explicitly opt-out of automatic window tabbing...
+	// It should respect the userTabbingPreference... see below
+	// https://developer.apple.com/library/archive/releasenotes/AppKit/RN-AppKitOlderNotes/index.html
 	if ([NSWindow respondsToSelector:@selector(allowsAutomaticWindowTabbing)])
-		NSWindow.allowsAutomaticWindowTabbing = NO;
-#endif
+		[NSWindow setAllowsAutomaticWindowTabbing:NO];
 
 	// Remove the "Enter Full Screen" menu item from the "View" menu
 	[[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"NSFullScreenMenuItemEverywhere"];
 }
+
+
+bool appleUserTabbingPreferenceAlways() {
+	return [NSWindow respondsToSelector:@selector(userTabbingPreference)] &&
+		[NSWindow userTabbingPreference] == NSWindowUserTabbingPreferenceAlways;
+}