Nested X-Server is running a X serverroot 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:
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.
If you ever wondered what combination of some colors would look like but did not really feel like setting them in your xterm just to check them out. Or if you wanted to know about all the colors on you X window system then you can install this utility called xcolorsel.
You will need to setup the rpm-shere repo for this.
Using this tool is very intuitive, just select the color and then press set as foreground/background to check how the color combination would look.