Add ability to change macOS WM theme (bug#27973)

* src/frame.c (make_frame, frame_parms, syms_of_frame)
[NS_IMPL_COCOA]: Add ns-appearance and ns-transparent-titlebar
options.
* src/frame.h (ns_appearance_type) [NS_IMPL_COCOA]: Add enum to
represent NSAppearance options.
(struct frame) [NS_IMPL_COCOA]: Add ns_appearance and
ns_transparent_titlebar frame parameters.
* src/nsfns.m (ns_frame_parm_handlers) [NS_IMPL_COCOA]: Add
ns_set_appearance and ns_set_transparent_titlebar handlers.
(Sx_create_frame): Handle ns-appearance and ns-transparent-titlebar
frame parameters.
(Qdark): Add new symbol for use with ns-appearance.
* src/nsterm.h (ns_set_appearance, ns_set_transparent_titlebar)
[NS_IMPL_COCOA]: Add prototypes.
* src/nsterm.m (ns_set_appearance, ns_set_transparent_titlebar)
[NS_IMPL_COCOA]: New functions.
(initFrameFromEmacs) [NS_IMPL_COCOA]: Handle ns-appearance and
ns-transparent-titlebar frame parameters.
* doc/lispref/frames.texi (Window Management Parameters): Document
ns-apperance and ns-transparent-titlebar.

1 files changed, 14 insertions, 0 deletions

diff --git a/doc/lispref/frames.texi b/doc/lispref/frames.texi
index b430f7c6fad..6431bbdedb9 100644
--- a/doc/lispref/frames.texi
+++ b/doc/lispref/frames.texi
@@ -2125,6 +2125,20 @@ Specifying this lets you create an Emacs window inside some other
 application's window.  (It is not certain this will be implemented; try
 it and see if it works.)
 @end ignore
+
+@vindex ns-appearance, a frame parameter
+@item ns-appearance
+Only available on macOS, if set to @code{dark} draw this frame's
+window-system window using the ``vibrant dark'' theme, otherwise use
+the system default.  The ``vibrant dark'' theme can be used to set the
+toolbar and scrollbars to a dark appearance when using an Emacs theme
+with a dark background.
+
+@vindex ns-transparent-titlebar, a frame parameter
+@item ns-transparent-titlebar
+Only available on macOS, if non-@code{nil}, set the titlebar and
+toolbar to be transparent.  This effectively sets the background color
+of both to match the Emacs background color.
 @end table