Open file or application as root from GUI
To run GUI applications with elevated permissions, you can use the gksu command:
You can check to see if it's installed with which gksu and if so it will output the path to the command. If not you can install it with the command sudo apt-get gksu
$ gksu nautilus # browse files as root
$ gksu gedit /etc/fstab # edit file as root
This command is a frontend to the su and sudo commands, designed for running graphical programs, so it is used the same way as them. See the man page for more information.