Improve locked narrowing around low-level hooks.

* src/buffer.c (syms_of_buffer): Two new variables,
'long-line-locked-narrowing-region-size' and
'long-line-locked-narrowing-bol-search-limit', to make the locked
narrowing around low-level hooks configurable.

Increase the default value of 'long-line-threshold'.  After
carefully considering the (few) bug reports about long line
optimizations, I concluded that the previous default value was too
low.

* src/xdisp.c (get_locked_narrowing_begv)
(get_locked_narrowing_zv): Two new functions.
(handle_fontified_prop, reseat): Use them.

* src/keyboard.c (safe_run_hooks_maybe_narrowed): Use them.

* src/dispextern.h (struct it): Add two new fields to store the
values returned by these functions.
Make them externally visible.

* src/editfns.c: (Fsave_restriction): Update docstring.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 4b35a044eb0..cb308f5bfc1 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -1911,8 +1911,8 @@ safe_run_hooks_maybe_narrowed (Lisp_Object hook, struct window *w)
   specbind (Qinhibit_quit, Qt);
 
   if (current_buffer->long_line_optimizations_p)
-    narrow_to_region_locked (make_fixnum (get_narrowed_begv (w, PT)),
-                             make_fixnum (get_narrowed_zv (w, PT)),
+    narrow_to_region_locked (make_fixnum (get_locked_narrowing_begv (PT)),
+                             make_fixnum (get_locked_narrowing_zv (PT)),
                              hook);
 
   run_hook_with_args (2, ((Lisp_Object []) {hook, hook}),