Visualbell not working

[ambadyanands]

Neovim version (nvim -v)

0.7.2

Vim (not Nvim) behaves the same?

no, vim 9.0

Operating system/version

Arch Linux

Terminal name/version

kitty 0.26.2

$TERM environment variable

xterm-kitty

Installation

Arch official repository (community)

How to reproduce the issue

nvim --clean
:set belloff=""
:set visualbell
Press <Esc> a couple of times from normal mode.

Expected behavior

The screen will flash.

Actual behavior

No UI change. Also tried :set errorbells, no change.

[zeertzjq]

I tried the following in kitty. It is strange that tput flash flashes the screen, but printf '\x1b[?5h\x1b[?5l' doesn't, despite outputing exactly the same bytes.

[zeertzjq]

Oh, there needs to be a delay between \x1b[?5h and \x1b[?5l, but Nvim always passes NULL as pad to unibi_format(), so padding instructions are always ignored.

[zeertzjq]

Minimum patch to make this work:

diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index 73f47f2b7..664b904d9 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -1616,7 +1616,7 @@ static void unibi_goto(UI *ui, int row, int col)
       memset(&vars, 0, sizeof(vars)); \
       data->cork = true; \
 retry: \
-      unibi_format(vars, vars + 26, str, data->params, out, ui, NULL, NULL); \
+      unibi_format(vars, vars + 26, str, data->params, out, ui, pad, ui); \
       if (data->overflow) { \
         data->bufpos = orig_pos; \
         flush_buf(ui); \
@@ -1658,6 +1658,12 @@ static void out(void *ctx, const char *str, size_t len)
   data->bufpos += len;
 }
 
+static void pad(void *ctx, size_t delay, int scale, int force)
+{
+  flush_buf(ctx);
+  uv_sleep((unsigned)(delay / 10));
+}
+
 static void unibi_set_if_empty(unibi_term *ut, enum unibi_string str, const char *val)
 {
   if (!unibi_get_str(ut, str)) {

Using uv_sleep() is probably not the right way to sleep here.