Allow aborting redisplay stuck in 'parse-partial-sexp'

* src/xdisp.c (display_working_on_window_p): New global variable.
(unwind_display_working_on_window): New function.
* src/keyboard.c (command_loop_1): Reset
'display_working_on_window_p' before and after executing commands.
* src/window.c (Frecenter, window_scroll, displayed_window_lines):
* src/indent.c (Fvertical_motion): Set
'display_working_on_window_p' before calling 'start_display'.
* src/syntax.c (scan_sexps_forward): Call 'update_redisplay_ticks'
after finishing the loop.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/indent.c b/src/indent.c
index 51f6f414de3..7d9f0fe8b00 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -2177,6 +2177,8 @@ whether or not it is currently displayed in some window.  */)
 	line_number_display_width (w, &lnum_width, &lnum_pixel_width);
       SET_TEXT_POS (pt, PT, PT_BYTE);
       itdata = bidi_shelve_cache ();
+      record_unwind_protect_void (unwind_display_working_on_window);
+      display_working_on_window_p = true;
       start_display (&it, w, pt);
       it.lnum_width = lnum_width;
       first_x = it.first_visible_x;