Today I discovered a new and great tool it is called xnest, well and what this tool lets you do?

I am going to show you a screenshot so you can see by yourself. xnest in action

Well and how to do it?

Install xnest

apt-get install xnest

and then run this command

gdmflexiserver --xnest

you can then login with a different user and have one session nested into the original one.