emacs-25.2-mac-6.3-no-title-bar.patch

diff --git a/lisp/cus-start.el b/lisp/cus-start.el
index 4df6781243..5afd89a473 100644
--- a/lisp/cus-start.el
+++ b/lisp/cus-start.el
@@ -558,6 +558,7 @@ minibuffer-prompt-properties--setter
 	     (mac-pass-command-to-system mac boolean "22.1")
 	     (mac-pass-control-to-system mac boolean "22.1")
 	     (mac-drawing-use-gcd mac boolean "24.4")
+	     (mac-use-title-bar mac boolean "25.2")
 	     (mac-frame-tabbing mac (choice (const automatic) (const inverted)
                                             (const nil) (const t)) "24.5")
              (debug-on-event debug
diff --git a/src/macappkit.m b/src/macappkit.m
index b3905f12a9..6ddecb9a9a 100644
--- a/src/macappkit.m
+++ b/src/macappkit.m
@@ -1824,6 +1824,16 @@ - (void)showMenuBar
 
 @implementation EmacsWindow
 
+- (BOOL)canBecomeKeyWindow
+{
+  return YES;
+}
+
+- (BOOL)canBecomeMainWindow
+{
+  return [self isVisible];
+}
+
 - (instancetype)initWithContentRect:(NSRect)contentRect
 			  styleMask:(NSWindowStyleMask)windowStyle
 			    backing:(NSBackingStoreType)bufferingType
@@ -2190,9 +2200,13 @@ - (void)setupWindow
       else
 	{
 	  windowClass = [EmacsWindow class];
-	  windowStyle = (NSWindowStyleMaskTitled | NSWindowStyleMaskClosable
-			 | NSWindowStyleMaskMiniaturizable
-			 | NSWindowStyleMaskResizable);
+          if (mac_use_title_bar)
+            windowStyle = (NSWindowStyleMaskTitled | NSWindowStyleMaskClosable
+                           | NSWindowStyleMaskMiniaturizable
+                           | NSWindowStyleMaskResizable);
+          else
+            windowStyle = (NSWindowStyleMaskBorderless | NSWindowStyleMaskResizable
+                           | NSWindowStyleMaskMiniaturizable);
 	}
     }
   else
diff --git a/src/macterm.c b/src/macterm.c
index 6c406e664e..926f0bafbf 100644
--- a/src/macterm.c
+++ b/src/macterm.c
@@ -6168,4 +6168,14 @@ tabbing is disallowed and preferred, respectively.
 
 This variable has no effect on OS X 10.11 and earlier.  */);
   Vmac_frame_tabbing = Qautomatic;
+
+  DEFVAR_BOOL ("mac-use-title-bar", mac_use_title_bar,
+     doc: /*Non-nil means to include the title bar on frames.  Nil means to
+omit the title bar on OSX >= 10.7.  This variable is ignored on OSX <
+10.7. Note that the first frame per emacs session (unless it is an
+emacsclient) will use the default value of this variable (nil--do not
+include a title bar), ignoring (!) the user-set value of this
+variable. This is almost certainly due to a bug in the patch adding
+this variable. Default is nil.*/);
+  mac_use_title_bar = false;
 }

This patch based on braham-snyder's no-title-bar patch for Emacs NS port(official trunk) and Jan Jungnickel's patch for earlier Mac port version

It fails when using --HEAD option