engine: update active preedit capability

strans.c

@@ -783,6 +783,17 @@ meaningful(Keyreq *kr)
 	return kr->ks != 0 && !ismodkey(kr->ks);
 }
 
+static int
+setactivecap(int cap)
+{
+	int old;
+
+	old = activecap & Cclientpreedit;
+	activecap &= ~Cclientpreedit;
+	activecap |= cap & Cclientpreedit;
+	return old != (activecap & Cclientpreedit);
+}
+
 static void
 imhandlekey(Keyreq *kr)
 {
@@ -809,13 +820,24 @@ imhandlekey(Keyreq *kr)
 			show();
 		}
 		break;
+	case Keycap:
+		res.eaten = 0;
+		if(activeowner != nil && kr->owner == activeowner){
+			res.eaten = 1;
+			if(setactivecap(kr->cap))
+				show();
+		}
+		break;
 	case Keypress:
 		res.eaten = 0;
+		if(activeowner != nil && kr->owner == activeowner &&
+		   setactivecap(kr->cap))
+			show();
 		if(meaningful(kr)){
 			if(kr->owner != activeowner){
 				reset();
 				activeowner = kr->owner;
-				activecap = kr->cap;
+				activecap = kr->cap & Cclientpreedit;
 				caret = kr->caret;
 			}else if(kr->caret.valid)
 				caret = kr->caret;