Nested X-Server is running a X server root window within your running X-windows session like Gnome or KDE. This could be useful if you want to keep all you ssh windows in one window or maybe run all you IRC, firefox, chat and others inside one window, or maybe run another window manager itself.
Lets first install ::
sudo yum install xorg-x11-server-Xephyr
Once done, you can define an alias to do the magic with your nested server. So, lets define an alias:
alias xlxc='Xephyr -title -resizeable -host-cursor -screen 1024x768 +extension randr +xinerama -ac :11.0& DISPLAY=:11.0 xterm &'
This will open a new x-server window with Xephyr and then open a terminal inside it. Once in, make sure to set your DISPAY variable in the xterm so that all other apps started from the terminal start in the Xephyr window only.