There is actually a simple way to make root available for gui logon in Mandrake.
Go to the "Configure Your Desktop" app. (In 10.1 it is "Start --> System --> Configuration --> Configure your desktop".) Open the '+' button beside "System" in the Index on the left. Click on "Login Manager". In the panel on the right, click the button at the bottom labeled "Administrator Mode". Enter your root password in the dialog box. Then select the tab "Users". In the middle is a panel listing all users. UN-check the box beside "root" to enable it to be displayed by the login manager.
Click "Apply", close the window, log out, and you should have the option of "root" now available.
Edit: On the other hand, you should not normally log in as root, anyway.
Major security hole! The *best* way is to open a terminal window in your gui, and do a "su" command. Then, from that window, as root, do your editing, wither directly in the window using "vi", or "nano", or whatever editor you like, or by issuing a command like "kwrite <filename>" to edit <filename> in a KWrite window. Or you could use the command "kdesu kwrite" to run kwrite as root, from your login.