Forums Bug Reports [6.17] multibyte display option reversed

option => irc => messages => multibyte display
the effect is reversed against what is was.
check = bad multibyte with long line
uncheck = good

utf-8 displaying isn't relatived to the this bug

If UTF-8 display and multibyte display are both enabled, when typing multibyte character(e.g.: Chinese) with Ctrl+B, +U or +K(i.e. bold, underline and colors), the nick(<nick> text) will be disappeared.

Try: (the following text is in Big-5 coding)
¤µ¤é¬O¤G¹s¹s¤»¦~¤G¤ë¤Q¤K¤é
12¤µ¤é¬O¤G¹s¹s¤»¦~¤G¤ë¤Q¤K¤é

Either UTF-8 display or multibyte display is enabled, this problem is not happened.

Chinese Simplified
[130451] -NickServ- 6&#23494;&#30721;&#27491;&#30830;&#65292;&#24863;&#35874;&#24744;&#30340;&#20351;&#29992;&#12290;
is display as
6&#23494;&#30721;&#27491;&#30830;&#65292;&#24863;&#35874;&#24744;&#30340;&#20351;&#29992;&#12290;
when both "multibyte display" and "utf-8 display" is turned on.
but ok if either one turned off

(ie make Chinese character into &#23494; due to the encoding of this forum)
(use javascript:'&#23494;...' to show origin text if u want)