Using rxvt-unicode-9.11 and mc-4.7.5.2, and using zsh-4.3.11 as my login shell, I find that I get strange characters, eg รข instead of lines being drawn.
Interestingly however, launching urxvt from any root shell, and then running mc inside of that renders the lines correctly.
In Xdefaults I am not setting a font.
I thought that any child shells should inherit the same as the parent shell, but clearly here it is not.
Exports in parent:
COLON_SEPARATED=MOZ_PLUGIN_PATH
COLORFGBG='7;default'
COLORTERM=rxvt
CONFIG_PROTECT_MASK='/lib64/udev/rules.d /etc/dconf/db /etc/ca-certificates.conf'
CVS_RSH=ssh
DESKTOP_STARTUP_ID=awesome/urxvtc/2194-57-alipc-desktop-ex_TIME28147172
DISPLAY=:0.0
GDK_USE_XFT=1
GPG_AGENT_INFO=/tmp/gpg-CeLaPY/S.gpg-agent:2191:1
HOME=/home/ali
INFOPATH=/usr/share/info
JAVAC=/usr/bin/javac
JAVACMD=/usr/bin/java
JAVA_HOME=/usr/lib64/jdk
LANG=en_GB.utf8
LDPATH=/usr/local/lib:/usr/lib64/nss:/usr/lib64/vdpau:/usr/lib64/qt4
LESS='-R -M --shift 5'
LOGNAME=ali
MAIL=/var/mail/ali
MANPATH=/usr/local/share/man:/usr/share/man
MOZ_PLUGIN_PATH=/usr/lib64/mozilla/plugins:/opt/netscape/plugins
PAGER=/usr/bin/less
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/bin:/usr/lib64/jdk/bin:/usr/lib64/jre/bin:/opt/bin:/usr/lib64/jdk/bin:/usr/lib64/jre/bin
PWD=/home/ali
SHELL=/bin/zsh
SHLVL=2
SSH_AGENT_PID=2193
SSH_AUTH_SOCK=/tmp/ssh-RhQcEipf2192/agent.2192
TERM=rxvt-256color
TERMINFO=/usr/share/terminfo
USER=ali
WINDOWID=20972128
XAUTHORITY=/home/ali/.Xauthority
_=export
Exports in child:
COLON_SEPARATED=MOZ_PLUGIN_PATH
COLORFGBG='7;default'
COLORTERM=rxvt
CONFIG_PROTECT_MASK='/lib64/udev/rules.d /etc/dconf/db /etc/ca-certificates.conf'
CVS_RSH=ssh
DESKTOP_STARTUP_ID=awesome/urxvtc/2194-57-alipc-desktop-ex_TIME28147172
DISPLAY=:0.0
GDK_USE_XFT=1
GPG_AGENT_INFO=/tmp/gpg-CeLaPY/S.gpg-agent:2191:1
HOME=/home/ali
INFOPATH=/usr/share/info
JAVAC=/usr/bin/javac
JAVACMD=/usr/bin/java
JAVA_HOME=/usr/lib64/jdk
LANG=en_GB.utf8
LDPATH=/usr/local/lib:/usr/lib64/nss:/usr/lib64/vdpau:/usr/lib64/qt4
LESS='-R -M --shift 5'
LOGNAME=ali
MAIL=/var/mail/ali
MANPATH=/usr/local/share/man:/usr/share/man
MOZ_PLUGIN_PATH=/usr/lib64/mozilla/plugins:/opt/netscape/plugins
OLDPWD=/home/ali
PAGER=/usr/bin/less
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/bin:/usr/lib64/jdk/bin:/usr/lib64/jre/bin:/opt/bin:/usr/lib64/jdk/bin:/usr/lib64/jre/bin
PWD=/home/ali
SHELL=/bin/zsh
SHLVL=4
SSH_AGENT_PID=2193
SSH_AUTH_SOCK=/tmp/ssh-RhQcEipf2192/agent.2192
STY=27048.pts-2.alipc-desktop-ex
TERM=rxvt-256color
TERMINFO=/usr/share/terminfo
USER=ali
WINDOW=0
WINDOWID=27262984
XAUTHORITY=/home/ali/.Xauthority
_=export
Thanks.
Edit: more information + combinations: .zshrc:
# The following lines were added by compinstall
zstyle ':completion:*' completer _expand _complete _ignored
zstyle ':completion:*' group-name ''
zstyle ':completion:*' list-colors ''
zstyle ':completion:*' menu select=long
zstyle ':completion:*' select-prompt %SScrolling active: current selection at %p%s
zstyle ':completion:*' use-compctl false
zstyle :compinstall filename '/home/ali/.zshrc'
autoload -U zutil
autoload -Uz compinit
autoload -U complist
compinit
autoload -U colors
colors
# End of lines added by compinstall
# Lines configured by zsh-newuser-install
HISTFILE=~/.histfile
HISTSIZE=1000
SAVEHIST=1000
setopt appendhistory autocd extendedglob notify
unsetopt beep
bindkey -v
# End of lines configured by zsh-newuser-install
#export PS1="%n#%d>"
PROMPT="%{$fg[red]%}%n%{$reset_color%}@%{$fg[blue]%}%m %{$fg[yellow]%}%d %{$reset_color%}%#"
RPROMPT="[%{$fg[yellow]%}%T%{$reset_color%}]"
locale -a: C en_GB.utf8 en_US.utf8 POSIX
exports from 'urxvt -e zsh -f': - A working set!
COLORFGBG='7;default'
COLORTERM=rxvt
DESKTOP_STARTUP_ID=awesome/urxvt/2199-28-alipc-desktop-ex_TIME11280170
DISPLAY=:0.0
GPG_AGENT_INFO=/tmp/gpg-d5ZFvz/S.gpg-agent:2196:1
HOME=/home/ali
LOGNAME=ali
MAIL=/var/mail/ali
PATH=/bin:/usr/bin:/usr/local/bin
PWD=/home/ali
SHELL=/bin/zsh
SHLVL=2
SSH_AGENT_PID=2198
SSH_AUTH_SOCK=/tmp/ssh-sPZhKOhV2197/agent.2197
TERM=rxvt-unicode-256color
TERMINFO=/usr/share/terminfo
USER=ali
WINDOWID=23068680
XAUTHORITY=/home/ali/.Xauthority
_=export
Note: I did try setting my TERM via .Xdefaults, to the one that worked in the 'clean' window:
urxvt*termName: rxvt-unicode-256color
Though this had no effect, so it is not TERM that affects this.