doing that is almost NEVER needed .There are a few times like a new install and fixing something ) that it MIGHT ??? be a little bit easier ?????
but if the gui IS running WHY even bother logging OUT and then logging BACK IN - that is a wast of time
use "su -" to start gedit or kwright or emacs ( or nano or vi)
Or if one is " desperate " and fending for a gui( read junky fending for a fix ) launch nautilus or dolphin with "su -"
Admittedly i run nautilus as root from time to time ( manually installing things and making links ) .Every know and then it is easier
BUT NOT logging out and logging back in as root -- that dose not even make since .