Hello!
How to reproduce found bug:
1. Exec command "/whois NickName"
[22:37] NickName is ~bill@host001.ms.net * realname
[22:37] NickName on #channel01 +#channel02 %#channel03 @#channel04
[22:37] NickName using irc.mirc.net WDC server of mIRC IRC
[22:37] NickName has been idle 45hrs 18mins 52secs, signed on Wed Jan 04 01:17:59 2017
[22:37] NickName End of WHOIS list.
2. Try to double-click or right-click on +#channel02