From d7c4d42f41eb0cfbbb38686da4410959fa016beb Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 9 Jul 2025 12:49:12 +0530
Subject: [PATCH] Fix #8794

---
 docs/changelog.rst    |  2 +-
 kitty/screen.c        |  2 +-
 kitty_tests/screen.py | 12 ++++++++++++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 341a3b72a..7a21e558e 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -126,7 +126,7 @@ Detailed list of changes
 - Wayland GNOME: Fix incorrect OS Window tracking because GNOME has started
   activating windows on non-current workspaces (:iss:`8716`)
 
-- Fix a regression in 0.40.0 that broke rendering of VS15 variation selectors in some circumstances (:iss:`8731`)
+- Fix a regression in 0.40.0 that broke rendering of VS15 variation selectors in some circumstances (:iss:`8731`, :iss:`8794`)
 
 - Fix a regression in 0.40.0 that broke serialization of tab characters as ANSI text (:iss:`8741`)
 
diff --git a/kitty/screen.c b/kitty/screen.c
index 2d5148150..9d2b385d1 100644
--- a/kitty/screen.c
+++ b/kitty/screen.c
@@ -866,7 +866,7 @@ halve_multicell_width(Screen *self, index_type x_, index_type y_) {
     int y_max_limit = MIN(self->lines, y_ + cp[x_].scale);
     for (int y = y_min_limit + 1; y < y_max_limit; y++) {
         Line *line = range_line_(self, y); cp = line->cpu_cells; gp = line->gpu_cells;
-        for (index_type x = 0; x < half_x_limit; x++) cp[x].width = new_width;
+        for (index_type x = x_; x < half_x_limit; x++) cp[x].width = new_width;
         for (index_type x = half_x_limit; x < x_limit; x++) {
             cp[x] = (CPUCell){0}; clear_sprite_position(gp[x]);
         }
diff --git a/kitty_tests/screen.py b/kitty_tests/screen.py
index 9d849411c..fb0affac5 100644
--- a/kitty_tests/screen.py
+++ b/kitty_tests/screen.py
@@ -710,12 +710,24 @@ class TestScreen(BaseTest):
         self.ae(s.text_for_selection(), ('a\u00adb',))
 
     def test_variation_selectors(self):
+        s = self.create_screen(cols=8)
+        def widths(text, *widths):
+            s.reset()
+            s.draw(text)
+            def w(x):
+                c = s.cpu_cells(0, x)
+                return (c['mcd'] or {'width': 1})['width']
+            actual = tuple(w(x) for x in range(len(widths)))
+            self.ae(widths, actual)
+        widths('\u4e00\u4e00\u26ab\ufe0e', 2, 2, 2, 2, 1)
+
         s = self.create_screen()
         def tt(text_to_draw):
             s.reset()
             s.draw(text_to_draw)
             self.ae(str(s.line(0)), text_to_draw)
         tt('abc\U0001f44d\ufe0ed')
+
         def t(*a):
             s.reset()
             for i in range(0, len(a), 2):