<NME> xdummy.conf
<BEF> [program:xdummy]
command=bash -l -c "xinit -- :0 -nolisten tcp vt$XDG_VTNR -noreset +extension GLX +extension RANDR +extension RENDER +extension XFIXES"
environment=HOME=/home/user,USER=user,QT_X11_NO_MITSHM=1
directory=/home/user
autorestart=true
stdout_logfile=/var/log/supervisor/xdummy.log
redirect_stderr=true

<MSG> Run the X session as "user" instead of root..

<DFF> @@ -1,5 +1,6 @@
 [program:xdummy]
 command=bash -l -c "xinit -- :0 -nolisten tcp vt$XDG_VTNR -noreset +extension GLX +extension RANDR +extension RENDER +extension XFIXES"
+user=user
 environment=HOME=/home/user,USER=user,QT_X11_NO_MITSHM=1
 directory=/home/user
 autorestart=true

Run the X session as "user" instead of root..