You can add a new option for the controls setting in the Theme preference tool. Controls options reside in the /usr/share/themes directory. The typical structure of a controls option in the file system is as follows:
/usr/share/themes/option-name/gtk-2.0/gtkrc
/usr/share/themes/option-name/pixmaps/*.*
Typically, a new option for the controls setting is supplied as a .tar.gz file. To install the new controls option, unzip the .tar.gz file, then untar the .tar file into the /usr/share/themes directory.
Users can install their own options for the controls setting. If a user installs an option for the controls setting, the option is stored in the $HOME/.themes directory.