macOS: Disable cocoa tabs

kitty has its own tabs, and macOS inserts confusing menu entries for its
non-functional tabs into the global menu. So disable tabs. Fixes #3325

docs/changelog.rst

@@ -75,6 +75,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
   and CascadiaCode. Now such ligatures are detected based on glyph naming
   convention. This removes the gap in the ligatures at cell boundaries (:iss:`2695`)
 
+- macOS: Disable the native operating system tabs as they are non-functional
+  and can be confusing (:iss:`3325`)
+
 
 0.19.3 [2020-12-19]
 -------------------

glfw/cocoa_window.m

@@ -1387,7 +1387,10 @@ void _glfwPlatformUpdateIMEState(_GLFWwindow *w, int which, int a, int b, int c,
                         initWindow:(_GLFWwindow *)initWindow
 {
     self = [super initWithContentRect:contentRect styleMask:style backing:backingStoreType defer:NO];
-    if (self != nil) glfw_window = initWindow;
+    if (self != nil) {
+        glfw_window = initWindow;
+        self.tabbingMode = NSWindowTabbingModeDisallowed;
+    }
     return self;
 }