diff --git a/strans.c b/strans.c
index 60c45e6..510b911 100644
--- a/strans.c
+++ b/strans.c
@@ -7,6 +7,7 @@ static void *activeowner;
 static int activecap;
 static Caret caret;
 static u32int dictseq;
+static int candidatechosen;
 static void dictqmap(Im*);
 static void dictqjp(Im*);
 static void backjp(Im*);
@@ -38,6 +39,7 @@ clearkouho(void)
 	dictseq++;
 	im.nkouho = 0;
 	im.sel = -1;
+	candidatechosen = 0;
 }
 
 static void
@@ -83,6 +85,7 @@ movekouho(int delta)
 		im.sel = 0;
 	if(im.sel >= im.nkouho)
 		im.sel = im.nkouho - 1;
+	candidatechosen = 1;
 }
 
 static int
@@ -154,36 +157,43 @@ setkouho(Dictres *res)
 }
 
 static void
-show(void)
+snapshot(Drawcmd *dc)
 {
-	static Drawcmd old;
-	Drawcmd dc;
 	Str pre;
 	int i, first, n;
 
-	sclear(&dc.pre);
+	memset(dc, 0, sizeof *dc);
 	if(search.lang)
 		pre = search.text;
 	else
 		impre(&pre);
 	if(!(activecap & Cclientpreedit)){
 		if(search.lang || isjp(&im) || im.l->map == nil ||
-		   !mapget(im.l->map, &pre, &dc.pre))
-			dc.pre = pre;
+		   !mapget(im.l->map, &pre, &dc->pre))
+			dc->pre = pre;
 	}
 	first = pagefirst();
 	n = im.nkouho - first;
 	if(n > Maxdisp) n = Maxdisp;
-	dc.nkouho = n;
-	dc.sel = im.sel >= 0 ? im.sel - first : -1;
-	dc.first = first;
-	dc.total = im.nkouho;
-	dc.caret = caret;
+	dc->nkouho = n;
+	dc->sel = im.sel >= 0 ? im.sel - first : -1;
+	dc->first = first;
+	dc->total = im.nkouho;
+	dc->caret = caret;
 	for(i = 0; i < n; i++)
-		dc.kouho[i] = im.kouho[first + i];
-	if(dc.pre.n == 0 && n == 0 && !visible)
+		dc->kouho[i] = im.kouho[first + i];
+}
+
+static void
+redraw(void)
+{
+	static Drawcmd old;
+	Drawcmd dc;
+
+	snapshot(&dc);
+	if(dc.pre.n == 0 && dc.nkouho == 0 && !visible)
 		return;
-	visible = dc.pre.n != 0 || n != 0;
+	visible = dc.pre.n != 0 || dc.nkouho != 0;
 	/* imthread is the sole producer; keep only the newest pending draw. */
 	while(channbrecv(drawc, &old) > 0)
 		;
@@ -200,7 +210,6 @@ reset(void)
 	sclear(&search.text);
 	memset(&caret, 0, sizeof caret);
 	clearkouho();
-	show();
 }
 
 static void
@@ -227,7 +236,6 @@ dictqmap(Im *im)
 	Str dict;
 
 	clearkouho();
-	show();
 	if(im->l->map == nil)
 		return;
 	if(!mapget(im->l->map, &im->pre, &dict))
@@ -241,7 +249,6 @@ dictqjp(Im *im)
 	Str reading;
 
 	clearkouho();
-	show();
 	if(im->l->dict == nil || !jpreading(im, &reading) || reading.n == 0)
 		return;
 	dictsend(im, &reading);
@@ -260,19 +267,25 @@ setlang(int c)
 }
 
 static void
-commit(Str *com)
+commitim(Im *p, Str *com)
 {
 	Str val;
 
-	if(isjp(&im)){
-		jpreading(&im, &val);
+	if(isjp(p)){
+		jpreading(p, &val);
 		sappend(com, &val);
-	}else if(im.l->map != nil && mapget(im.l->map, &im.pre, &val))
+	}else if(p->l->map != nil && mapget(p->l->map, &p->pre, &val))
 		sappend(com, &val);
 	else
-		sappend(com, &im.pre);
-	sclear(&im.pre);
-	sclear(&im.raw);
+		sappend(com, &p->pre);
+	sclear(&p->pre);
+	sclear(&p->raw);
+}
+
+static void
+commit(Str *com)
+{
+	commitim(&im, com);
 }
 
 static void
@@ -302,43 +315,39 @@ keeptail(Str *s)
 }
 
 static int
-dotransjp(Rune c, Str *com)
+transjp(Im *p, Rune c, Str *com)
 {
 	Str key, mapped;
 
-	if(c == '\'' && im.raw.n == 1 && im.raw.r[0] == 'n'){
-		if(mapget(im.l->map, &im.raw, &mapped))
-			sappend(&im.pre, &mapped);
-		sclear(&im.raw);
-		dictqjp(&im);
+	if(c == '\'' && p->raw.n == 1 && p->raw.r[0] == 'n'){
+		if(mapget(p->l->map, &p->raw, &mapped))
+			sappend(&p->pre, &mapped);
+		sclear(&p->raw);
 		return 1;
 	}
-	key = im.raw;
+	key = p->raw;
 	if(key.n < Maxrunes)
 		sputr(&key, c);
 	sclear(&mapped);
-	if(maplookup(im.l->map, &key, &mapped)){
-		im.raw = key;
+	if(maplookup(p->l->map, &key, &mapped)){
+		p->raw = key;
 		if(issmalltsu(&mapped)){
-			sappend(&im.pre, &mapped);
-			keeptail(&im.raw);
+			sappend(&p->pre, &mapped);
+			keeptail(&p->raw);
 		}
-		dictqjp(&im);
 		return 1;
 	}
-	if(im.raw.n != 0 && mapget(im.l->map, &im.raw, &mapped)){
-		sappend(&im.pre, &mapped);
-		sclear(&im.raw);
+	if(p->raw.n != 0 && mapget(p->l->map, &p->raw, &mapped)){
+		sappend(&p->pre, &mapped);
+		sclear(&p->raw);
 		sclear(&key);
 		sputr(&key, c);
-		if(maplookup(im.l->map, &key, &mapped)){
-			im.raw = key;
-			dictqjp(&im);
+		if(maplookup(p->l->map, &key, &mapped)){
+			p->raw = key;
 			return 1;
 		}
 	}
-	commit(com);
-	clearkouho();
+	commitim(p, com);
 	return 0;
 }
 
@@ -348,8 +357,14 @@ dotrans(Rune c, Str *com)
 	Emit e;
 	Str mapped;
 
-	if(isjp(&im))
-		return dotransjp(c, com);
+	if(isjp(&im)){
+		e.eat = transjp(&im, c, com);
+		if(e.eat)
+			dictqjp(&im);
+		else
+			clearkouho();
+		return e.eat;
+	}
 	e = im.l->trans(&im, c);
 	if(im.l->lang == LangVI){
 		if(e.s.n > 0 || !e.eat)
@@ -470,7 +485,7 @@ foldascii(Str *s)
 static void
 transstr(Lang *l, Str *raw, Str *out)
 {
-	static Im q;
+	Im q;
 	Emit e;
 	Str mapped;
 	int i;
@@ -482,6 +497,14 @@ transstr(Lang *l, Str *raw, Str *out)
 	}
 	memset(&q, 0, sizeof q);
 	q.l = l;
+	if(isjp(&q)){
+		for(i = 0; i < raw->n; i++)
+			if(!transjp(&q, raw->r[i], out) && out->n < Maxrunes)
+				sputr(out, raw->r[i]);
+		if(haspre(&q))
+			commitim(&q, out);
+		return;
+	}
 	for(i = 0; i < raw->n; i++){
 		e = l->trans(&q, raw->r[i]);
 		sappend(out, &e.s);
@@ -546,7 +569,6 @@ emojiquery(void)
 	}
 	search.text = rawhit || !localhit ? raw : local;
 	selectfirst();
-	show();
 }
 
 static void
@@ -562,7 +584,6 @@ hanjaquery(void)
 		setkouho(&res);
 	}else
 		clearkouho();
-	show();
 }
 
 static void
@@ -591,7 +612,6 @@ endsearch(void)
 	sclear(&search.raw);
 	sclear(&search.text);
 	clearkouho();
-	show();
 }
 
 static void
@@ -605,7 +625,6 @@ startsearch(int lang, Str *com)
 	search.lang = lang;
 	sclear(&search.raw);
 	sclear(&search.text);
-	show();
 }
 
 static void
@@ -638,7 +657,6 @@ searchkey(u32int ks, u32int mod, Str *com)
 		if(im.nkouho == 0)
 			return 1;
 		movekouho(n);
-		show();
 		return 1;
 	}
 	n = numberedkouho(ks, mod);
@@ -658,7 +676,6 @@ searchkey(u32int ks, u32int mod, Str *com)
 			im.sel = 0;
 		else
 			im.sel++;
-		show();
 		return 1;
 	}
 	if(ks == Kret){
@@ -712,7 +729,7 @@ searchkey(u32int ks, u32int mod, Str *com)
 }
 
 static int
-keystroke(u32int ks, u32int mod, Str *com)
+transition(u32int ks, u32int mod, Str *com)
 {
 	int n;
 	Rune c;
@@ -726,7 +743,6 @@ keystroke(u32int ks, u32int mod, Str *com)
 		if(im.nkouho == 0)
 			return 0;
 		movekouho(n);
-		show();
 		return 1;
 	}
 	n = numberedkouho(ks, mod);
@@ -736,7 +752,7 @@ keystroke(u32int ks, u32int mod, Str *com)
 		return 1;
 	}
 	if(ks == Ktab || ks == Kret){
-		if(im.sel >= 0 && im.sel < im.nkouho){
+		if(candidatechosen && im.sel >= 0 && im.sel < im.nkouho){
 			sappend(com, &im.kouho[im.sel]);
 			reset();
 			return 1;
@@ -779,12 +795,14 @@ keystroke(u32int ks, u32int mod, Str *com)
 			return 1;
 		}
 		if(getlang(c) != nil){
-			if(isjp(&im) && haspre(&im))
+			if(haspre(&im))
 				commit(com);
 			reset();
 			setlang(c);
 			return 1;
 		}
+		if(haspre(&im))
+			commit(com);
 		reset();
 		return 0;
 	}
@@ -814,10 +832,33 @@ keystroke(u32int ks, u32int mod, Str *com)
 	if(im.l->lang == LangKO)
 		ks = kokey(ks, mod);
 	n = dotrans(ks, com);
-	show();
 	return n;
 }
 
+static int
+keystrokeforce(u32int ks, u32int mod, Str *com, int force)
+{
+	Im oldim;
+	Search oldsearch;
+	int eaten, ncom;
+
+	oldim = im;
+	oldsearch = search;
+	ncom = com->n;
+	eaten = transition(ks, mod, com);
+	if(force || eaten || com->n != ncom ||
+	   memcmp(&oldim, &im, sizeof im) != 0 ||
+	   memcmp(&oldsearch, &search, sizeof search) != 0)
+		redraw();
+	return eaten;
+}
+
+static int
+keystroke(u32int ks, u32int mod, Str *com)
+{
+	return keystrokeforce(ks, mod, com, 0);
+}
+
 static void
 init(void)
 {
@@ -829,6 +870,7 @@ init(void)
 	activeowner = nil;
 	activecap = 0;
 	dictseq = 0;
+	candidatechosen = 0;
 	visible = 0;
 }
 
@@ -854,6 +896,7 @@ imhandlekey(Keyreq *kr)
 {
 	Keyres res;
 	void *oldowner;
+	int changed;
 
 	oldowner = activeowner;
 	sclear(&res.commit);
@@ -865,16 +908,19 @@ imhandlekey(Keyreq *kr)
 			reset();
 			activeowner = nil;
 			activecap = 0;
+			redraw();
 		}
 		break;
 	case Keyreset:
-		if(kr->owner == activeowner)
+		if(kr->owner == activeowner){
 			reset();
+			redraw();
+		}
 		break;
 	case Keycaret:
 		if(kr->owner == activeowner){
 			caret = kr->caret;
-			show();
+			redraw();
 		}
 		break;
 	case Keycap:
@@ -882,24 +928,33 @@ imhandlekey(Keyreq *kr)
 		if(activeowner != nil && kr->owner == activeowner){
 			res.eaten = 1;
 			if(setactivecap(kr->cap))
-				show();
+				redraw();
 		}
 		break;
 	case Keypress:
 		res.eaten = 0;
+		changed = 0;
 		if(activeowner != nil && kr->owner == activeowner &&
 		   setactivecap(kr->cap))
-			show();
+			changed = 1;
 		if(meaningful(kr)){
 			if(kr->owner != activeowner){
 				reset();
 				activeowner = kr->owner;
 				activecap = kr->cap & Cclientpreedit;
 				caret = kr->caret;
-			}else if(kr->caret.valid)
+				changed = 1;
+			}else if(kr->caret.valid){
 				caret = kr->caret;
-			res.eaten = keystroke(kr->ks, kr->mod, &res.commit);
-		}
+				changed = 1;
+			}
+			if(changed)
+				res.eaten = keystrokeforce(kr->ks, kr->mod,
+					&res.commit, 1);
+			else
+				res.eaten = keystroke(kr->ks, kr->mod, &res.commit);
+		}else if(changed)
+			redraw();
 		break;
 	}
 	if(activeowner != oldowner)
@@ -923,7 +978,7 @@ dictresult(Dictres *res)
 	   scmp(&res->key, &pre) != 0)
 		return;
 	setkouho(res);
-	show();
+	redraw();
 }
 
 void
diff --git a/tests/engine_test.c b/tests/engine_test.c
index 8d17391..f2f41da 100644
--- a/tests/engine_test.c
+++ b/tests/engine_test.c
@@ -8,6 +8,7 @@ int checkstr(struct ct*, char*, char*, Str*);
 Str shownpre(Im*);
 
 static int typekeys(struct ct*, char*, Str*);
+static int draindraw(Drawcmd*);
 
 void
 testengineinit(int lang)
@@ -417,7 +418,8 @@ engine_commit_contract(struct ct *t)
 	im.kouho[0] = mkstr("c1");
 	im.kouho[1] = mkstr("c2");
 	im.nkouho = 2;
-	im.sel = 1;
+	im.sel = 0;
+	CT_CHECK(t, keystroke(Kdown, 0, &com));
 	CT_CHECK(t, keystroke(Kret, 0, &com));
 	checkstr(t, "selected candidate", "c2", &com);
 	CT_EQ_INT(t, 0, im.pre.n);
@@ -484,6 +486,7 @@ engine_korean_modifiers_and_backspace(struct ct *t)
 		{ 'w', "ㅈ", "ㅉ" }, { 'o', "ㅐ", "ㅒ" },
 		{ 'p', "ㅔ", "ㅖ" },
 	};
+	Drawcmd dc;
 	Str com;
 	int i;
 
@@ -518,8 +521,11 @@ engine_korean_modifiers_and_backspace(struct ct *t)
 	sclear(&com);
 	if(typekeys(t, "rkr", &com)){
 		checkstr(t, "Korean engine preedit", "각", &im.pre);
+		draindraw(nil);
 		CT_CHECK(t, keystroke(Kback, 0, &com));
 		checkstr(t, "Korean final backspace", "가", &im.pre);
+		if(CT_CHECK(t, draindraw(&dc) == 1))
+			checkstr(t, "Korean backspace redraw", "가", &dc.pre);
 		CT_CHECK(t, keystroke(Kback, 0, &com));
 		checkstr(t, "Korean vowel backspace", "ㄱ", &im.pre);
 		CT_CHECK(t, keystroke(Kback, 0, &com));
@@ -578,10 +584,10 @@ engine_language_switch_state(struct ct *t)
 		{ "select Vietnamese", 'v', Mctrl, LangVI, "", "", "", 0 },
 		{ "Vietnamese a", 'a', 0, LangVI, "a", "a", "", 0 },
 		{ "Vietnamese tone", 's', 0, LangVI, "as", "as", "", 0 },
-		{ "switch to Korean", 's', Mctrl, LangKO, "", "", "", 1 },
+		{ "switch to Korean", 's', Mctrl, LangKO, "", "", "á", 1 },
 		{ "Korean initial", 'r', 0, LangKO, "ㄱ", "", "", 0 },
 		{ "Korean syllable", 'k', 0, LangKO, "가", "", "", 0 },
-		{ "switch to Vietnamese", 'v', Mctrl, LangVI, "", "", "", 0 },
+		{ "switch to Vietnamese", 'v', Mctrl, LangVI, "", "", "가", 0 },
 		{ "Vietnamese a again", 'a', 0, LangVI, "a", "a", "", 0 },
 		{ "Vietnamese tone again", 's', 0, LangVI, "as", "as", "", 0 },
 		{ "commit Vietnamese", Kret, 0, LangVI, "", "", "á", 0 },
@@ -632,6 +638,24 @@ engine_language_switch_state(struct ct *t)
 			break;
 		}
 	}
+
+	init();
+	im.l = getlang(LangKO);
+	sclear(&com);
+	if(typekeys(t, "rk", &com)){
+		CT_CHECK(t, !keystroke('p', Mctrl, &com));
+		checkstr(t, "Korean Ctrl passthrough", "가", &com);
+		CT_EQ_INT(t, 0, im.pre.n);
+	}
+	init();
+	im.l = &testvi;
+	sclear(&com);
+	if(typekeys(t, "as", &com)){
+		CT_CHECK(t, !keystroke('p', Mctrl, &com));
+		checkstr(t, "Vietnamese Ctrl passthrough", "á", &com);
+		CT_EQ_INT(t, 0, im.pre.n);
+		CT_EQ_INT(t, 0, im.raw.n);
+	}
 	vi->map = saved;
 }
 
@@ -644,6 +668,7 @@ struct Searchfix
 	Hmap	*dict;
 	int	activecap;
 	int	visible;
+	int	candidatechosen;
 };
 
 static int
@@ -691,7 +716,7 @@ checkcandidatepage(struct ct *t, char *where, int first, int n, int sel)
 	Drawcmd dc;
 	char want[8];
 
-	show();
+	redraw();
 	if(!CT_CHECK(t, draindraw(&dc) > 0))
 		return 0;
 	if(!CT_EQ_INT(t, n, dc.nkouho) || !CT_EQ_INT(t, sel, dc.sel) ||
@@ -732,10 +757,10 @@ engine_candidate_page_metadata(struct ct *t)
 
 	/* A clearing draw is the observable zero-candidate snapshot. */
 	candidatebegin(1);
-	show();
+	redraw();
 	draindraw(nil);
 	setcandidates(0);
-	show();
+	redraw();
 	if(CT_CHECK(t, draindraw(&dc) > 0)){
 		CT_EQ_INT(t, 0, dc.nkouho);
 		CT_EQ_INT(t, -1, dc.sel);
@@ -761,7 +786,7 @@ engine_candidate_page_snapshots(struct ct *t)
 		candidatebegin(totals[i]);
 		CT_EQ_INT(t, totals[i] == 0 ? -1 : 0, im.sel);
 		if(totals[i] == 0){
-			show();
+			redraw();
 			CT_EQ_INT(t, 0, draindraw(nil));
 			continue;
 		}
@@ -815,17 +840,39 @@ engine_candidate_page_movement(struct ct *t)
 void
 engine_candidate_completion(struct ct *t)
 {
+	static Rune keys[] = { Kret, Ktab };
+	Dictres res;
 	Str com;
+	int arrived, i;
+
+	for(i = 0; i < nelem(keys); i++)
+		for(arrived = 0; arrived < 2; arrived++){
+			init();
+			im.l = getlang(LangJP);
+			im.pre = mkstr("reading");
+			memset(&res, 0, sizeof res);
+			res.key = im.pre;
+			res.lang = LangJP;
+			res.seq = dictseq;
+			res.kouho[0] = mkstr("candidate");
+			res.nkouho = 1;
+			if(arrived)
+				dictresult(&res);
+			sclear(&com);
+			CT_CHECK(t, keystroke(keys[i], 0, &com));
+			if(!arrived)
+				dictresult(&res);
+			checkstr(t, "unselected candidate commits reading",
+				"reading", &com);
+			CT_EQ_INT(t, 0, im.nkouho);
+		}
 
 	candidatebegin(2);
+	im.pre = mkstr("reading");
 	sclear(&com);
+	CT_CHECK(t, keystroke(Kdown, 0, &com));
 	CT_CHECK(t, keystroke(Kret, 0, &com));
-	checkstr(t, "default candidate", "c1", &com);
-
-	candidatebegin(2);
-	sclear(&com);
-	CT_CHECK(t, keystroke(Ktab, 0, &com));
-	checkstr(t, "ordinary Tab candidate", "c1", &com);
+	checkstr(t, "explicit candidate", "c2", &com);
 
 	candidatebegin(2);
 	im.pre = mkstr("reading");
@@ -866,6 +913,7 @@ searchsave(Searchfix *f, int lang)
 	f->dict = f->dictlang->dict;
 	f->activecap = activecap;
 	f->visible = visible;
+	f->candidatechosen = candidatechosen;
 	draindraw(nil);
 }
 
@@ -908,6 +956,7 @@ searchend(Searchfix *f)
 	search = f->search;
 	activecap = f->activecap;
 	visible = f->visible;
+	candidatechosen = f->candidatechosen;
 }
 
 void
@@ -931,7 +980,7 @@ engine_popup_preedit_capability(struct ct *t)
 	res.nkouho = 1;
 	dictresult(&res);
 	im.sel = 0;
-	show();
+	redraw();
 	if(CT_CHECK(t, draindraw(&dc) > 0)){
 		CT_EQ_INT(t, 0, dc.pre.n);
 		CT_EQ_INT(t, 1, dc.nkouho);
@@ -1018,7 +1067,15 @@ engine_japanese_readings(struct ct *t)
 		{ "nnya", "んにゃ" },
 		{ "kin'youbi", "きんようび" },
 	};
-	Str com, shown;
+	static const struct {
+		char *raw;
+		char *want;
+	} replay[] = {
+		{ "kitte", "きって" },
+		{ "kanj", "かんj" },
+		{ "n'ya", "んや" },
+	};
+	Str com, raw, shown;
 	int i;
 
 	for(i = 0; i < nelem(cases); i++){
@@ -1033,6 +1090,11 @@ engine_japanese_readings(struct ct *t)
 		CT_CHECK(t, keystroke(Kret, 0, &com));
 		checkstr(t, "committed reading", cases[i].want, &com);
 	}
+	for(i = 0; i < nelem(replay); i++){
+		raw = mkstr(replay[i].raw);
+		transstr(getlang(LangJP), &raw, &shown);
+		checkstr(t, replay[i].raw, replay[i].want, &shown);
+	}
 }
 
 static int
@@ -1194,7 +1256,7 @@ engine_emoji_single_candidate(struct ct *t)
 		checkstr(t, "explicit candidate commit", "α", &com);
 		CT_CHECK(t, !search.lang);
 		CT_EQ_INT(t, LangKO, im.l->lang);
-		show();
+		redraw();
 		CT_CHECK(t, draindraw(&dc) > 0);
 		CT_EQ_INT(t, 0, dc.pre.n);
 		CT_EQ_INT(t, 0, dc.nkouho);