From 1c8d9fac0754199fa82c3f6210d7c3dfb350ad12 Mon Sep 17 00:00:00 2001
From: Hojun-Cho <ghwns6743@gmail.com>
Date: Mon, 17 Aug 2026 01:27:47 +0900
Subject: [PATCH] engine: Ctrl+Shift chords belong to the application

Ctrl+Shift+V switched to Vietnamese and ate the key, in every terminal
where it pastes; Ctrl+Shift+T and N opened no tab.  Only a plain
Ctrl+letter is a strans command now; a chord with Shift, Alt, or Super
commits what is pending and passes, as Alt and Super chords already did.
Caps Lock still works: the keysym's case never mattered.
---
 README.md           |  4 +++-
 strans.c            | 19 ++++++++++++++-----
 tests/engine_test.c | 10 +++++++---
 3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index f2bdae0..1540563 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,9 @@ Vietnamese Telex is also available as a compatibility mode.
 | `Ctrl+H` | One-shot Hanja search |
 
 A Korean keyboard's 한/영 key toggles Korean and English, and its 한자 key
-is `Ctrl+H`.
+is `Ctrl+H`. Only a plain `Ctrl` chord is a strans key: with `Shift`, `Alt`,
+or `Super` held it commits what is pending and goes to the application, so
+`Ctrl+Shift+V` still pastes.
 
 A complete Japanese reading shows its Kanji candidates with none chosen.
 `Space` chooses the first and then steps on, wrapping (`Shift+Space` steps
diff --git a/strans.c b/strans.c
index 9d71532..7135314 100644
--- a/strans.c
+++ b/strans.c
@@ -615,6 +615,16 @@ searchlang(Rune c)
 	return c == LangEMOJI || c == LangHANJA ? c : 0;
 }
 
+/*
+ * A chord with Alt or Super, or Ctrl with Shift, is the application's
+ * (Ctrl+Shift+V pastes); only a plain Ctrl+letter is a strans command.
+ */
+static int
+chord(u32int mod)
+{
+	return (mod & ~Mshift) != 0 && mod != Mctrl;
+}
+
 static void
 endsearch(void)
 {
@@ -722,12 +732,11 @@ searchkey(u32int ks, u32int mod, Str *com)
 		endsearch();
 		return 1;
 	}
-	if(ks >= Kspec || (ks < ' ' && !(mod & Mctrl)) ||
-	   (mod & (Malt|Msuper))){
+	if(ks >= Kspec || (ks < ' ' && !(mod & Mctrl)) || chord(mod)){
 		flush(com);
 		return 0;
 	}
-	if(mod & Mctrl){
+	if(mod == Mctrl){
 		c = ctrlkey(ks);
 		n = searchlang(c);
 		if(n != 0 && n != search.lang){
@@ -821,11 +830,11 @@ transition(u32int ks, u32int mod, Str *com)
 			reset();
 		return 1;
 	}
-	if(ks >= Kspec || (mod & (Malt|Msuper))){
+	if(ks >= Kspec || chord(mod)){
 		flush(com);
 		return 0;
 	}
-	if(mod & Mctrl){
+	if(mod == Mctrl){
 		c = ctrlkey(ks);
 		n = searchlang(c);
 		if(n != 0){
diff --git a/tests/engine_test.c b/tests/engine_test.c
index bb5675b..a0f5967 100644
--- a/tests/engine_test.c
+++ b/tests/engine_test.c
@@ -1636,16 +1636,20 @@ engine_emoji_preedit_languages(struct ct *t)
 		CT_CHECK(t, !keystroke(Kmodfirst+2, 0, &com));
 		impre(&im, &shown);
 		checkstr(t, "modifier preserves Japanese", "か", &shown);
-		CT_CHECK(t, keystroke('E', Mctrl|Mshift, &com));
+		CT_CHECK(t, keystroke('E', Mctrl, &com));
 		checkstr(t, "committed Japanese preedit", "か", &com);
 		CT_CHECK(t, search.lang);
 		CT_EQ_INT(t, LangJP, im.l->lang);
 		CT_CHECK(t, !keystroke('E', Mctrl|Malt, &com));
 		CT_EQ_INT(t, 0, search.lang);
-		CT_CHECK(t, keystroke('E', Mctrl|Mshift, &com));
+		CT_CHECK(t, keystroke('E', Mctrl, &com));
 		CT_CHECK(t, !keystroke('E', Mctrl|Msuper, &com));
 		CT_EQ_INT(t, 0, search.lang);
-		CT_CHECK(t, keystroke('E', Mctrl|Mshift, &com));
+		CT_CHECK(t, keystroke('E', Mctrl, &com));
+		CT_CHECK(t, !keystroke('V', Mctrl|Mshift, &com));
+		CT_EQ_INT(t, 0, search.lang);
+		CT_EQ_INT(t, LangJP, im.l->lang);
+		CT_CHECK(t, keystroke('E', Mctrl, &com));
 		CT_EQ_INT(t, LangJP, im.l->lang);
 		CT_CHECK(t, keystroke('a', 0, &com));
 		CT_CHECK(t, !keystroke(Kmodfirst+2, 0, &com));