Yes, there is. First, I assume you are logged in as user, not as root.
First thing to do is find the GUI editor executable you want to use.
Example: let's assume you are working in the KDE environment, and you want to use kwrite to edit the file.
We will start getting you some command-line experience, gently. Open a terminal window (the computer screen icon in the tray, with the scallop shell superimposed). Just click on it. When the screen is up, enter this command: which kwrite, and press enter. It should show you the path to the kwrite executable (by the way, you can do this for any application).
Now. You need to be able to edit a file which, normally, only the root (sysadmin) has permission to use. But, you can't do it in a GUI unless you give another command-line command first. Ready? Here it is. As user, give this command: xhost +localhost, and press enter.
Now su to root (that means, enter the su command and press enter, then enter the root password, and press enter again.
Now, you are root. Enter the entire path to the executable for the GUI editor you want to use, and when it opens, you are using it as root, not user. Click on File in the menubar, then Open, then browse to the file you want to edit as root. Save when done editing.
For safety sake, close and exit the application when you're done, and when the prompt returns in the term window, type 'exit' and press enter. That will return you to the user prompt, and you don't risk doing something disastrous as root, inadvertantly.