Add ns-click-through option to control activation click handling

* src/nsterm.m (acceptsFirstMouse):
Use ns_click_through variable instead of always returning YES.
(syms_of_nsterm): Define ns-click-through variable.

* lisp/cus-start.el: Add customization definition for ns-click-through.

* etc/NEWS: Document the new option.

etc/NEWS

@@ -29,6 +29,19 @@ applies, and please also update docstrings as needed.
 The traditional unexec dumper, deprecated since Emacs 27, has been
 removed.
 
+
+* MacOS/NS Changes in Emacs 31.1
+
+---
+** New user option 'ns-click-through' controls whether activation clicks
+are passed through to Emacs commands.
+When nil, clicking on an inactive Emacs frame will only activate it.
+When t (the default), the click will both activate the frame and be interpreted
+as a command.
+
++++
+** On Cocoa builds, stipples now render with color. (Bug#73384)
+
 ** Changed GCC default options on 32-bit x86 systems.
 When using GCC 4 or later to build Emacs on 32-bit x86 systems,
 'configure' now defaults to using the GCC options '-mfpmath=sse' (if the

lisp/cus-start.el

@@ -582,6 +582,12 @@ Leaving \"Default\" unchecked is equivalent with specifying a default of
              (ns-use-fullscreen-animation ns boolean "25.1")
              (ns-use-srgb-colorspace ns boolean "24.4")
              (ns-scroll-event-delta-factor ns float "29.1")
+
+             (ns-click-through
+	      ns (choice (const :tag "Never (nil)" :value nil)
+                  (const :tag "Always (t)" :value t))
+              "31.1")
+
 	     ;; process.c
 	     (delete-exited-processes processes-basics boolean)
              (process-error-pause-time processes-basics integer "29.1")

src/nsterm.m

@@ -6891,7 +6891,7 @@ - (BOOL)acceptsFirstMouse:(NSEvent *)theEvent
 {
   NSTRACE_MSG ("First mouse event: type=%ld, clickCount=%ld",
                [theEvent type], [theEvent clickCount]);
-  return YES;
+  return ns_click_through;
 }
 - (void)resetCursorRects
 {
@@ -11300,6 +11300,21 @@ Nil means use fullscreen the old (< 10.7) way.  The old way works better with
      doc: /* SKIP: real doc in xterm.c.  */);
   x_underline_at_descent_line = 0;
 
+  // TODO: add an "auto" mode that passes clicks through to "utility" UI
+  // elements, selectis windows, and so on, but doesn't pass them
+  // through for commands in general --- consistent with
+  // other applications.
+
+  DEFVAR_BOOL ("ns-click-through",
+	       ns_click_through,
+	       doc: /* Whether to pass activation clicks through to Emacs.
+When nil, if Emacs is not focused, the click that focuses Emacs will not
+be interpreted as a common.  If t, it will be.  For example, when nil,
+if Emacs is inactive, two clicks are needed to move point: the first to
+activate Emacs and the second to activate the mouse-1 binding.  When t,
+only a single click is needed.  */);
+  ns_click_through = YES;
+
   DEFSYM (Qx_underline_at_descent_line, "x-underline-at-descent-line");
 
   DEFVAR_LISP ("ns-scroll-event-delta-factor", Vns_scroll_event_delta_factor,