Created attachment 173156 [details]
Patch from upstream
Starting from version 2.2 tmux uses system functions to work with Unicode. On FreeBSD, wcwidth() returns -1 on some characters(like ''), so tmux cannot correctly draw this. Step to reproduce - type "echo '\U+E0A1'", you must see '' symbol but in tmux echoed empty line on 11-STABLE. This is a problem with FreeBSD system locale implementation, but upstream have workaround. Patch from upstream attached.
A commit references this bug:
Date: Thu Aug 4 13:19:34 UTC 2016
New revision: 419609
Fix some Unicode characters not displaying correctly.
Submitted by: Oleg Gushchenkov
Obtained from: https://github.com/tmux/tmux/commit/65e4c57d3a554940ed5cada6dfeff403ae8d9572
Sponsored by: Absolight