Wikipedia
Gconf-editor was an application for the GNOME desktop environment used to maintain the old and now discontinued GNOME registry gconf.
Gconf-editor gives users the ability to access settings stored in the XML-based GConf configuration database or registry. It is used primarily by developers to debug applications, or by power users to edit hidden and complex settings. It abstracts the values from the GConf database and presents them in an interface similar to Microsoft Windows' registry editor.
Traditional CLI (Command Line Interface) power users of GNOME have criticized it as an excuse to oversimplify the user interface and design for the lowest common denominator. Preferences such as turning off desktop icons or changing window button order are not available through a friendly graphical user interface (GUI), like other settings, but can only be changed using gconf-editor. GNOME core developers claim that the majority of users find lots of options and choices confusing and difficult to learn, and that so-called power users have little difficulty finding options using an application such as Gconf-editor.
Due to the controversy, other gconf tools have appeared, such as Gconfpref by MandrakeSoft. There are also patches for popular applications, which add the ability to change the hidden options from within the application itself, avoiding the need for gconf-editor.
There is also the dconf-editor for the dconf; dconf has replaced Gconf.