Clearlooks

Clearlooks is a theme for GTK, the main widget toolkit used by the GNOME desktop environment.

It is based on Red Hat's Bluecurve theme.

The creators of the Clearlooks GTK+ theme were Richard Stellingwerff and Daniel Borgmann; however, since 2005 the theme has been developed by GNOME, and current developers are Andrea Cimitan and Benjamin Berg.

Qt, versions 4.2 to 4.4, use a port of Clearlooks called Cleanlooks to better integrate with GTK applications.

Furthermore, a user by the name of jpfleury on Gnome-Look has recreated Clearlooks for GTK+ 3, called Clearlooks-Phenix.

Sample of the Clearlooks 2.20 theme with various applications
screenshot of LibreOffice 3.5.4.2 on Debian GNU/Linux 7.3 (wheezy) amd64 with GNOME 3.4.2 with theme Clearlooks-Phenix
A typical MATE desktop environment with the Clearlooks fork TraditionalOK as a standard theme