If the desktop themes that the GNOME desktop provides are not suitable for the needs of your users, you can create a custom desktop theme. To create a custom desktop theme, perform the following steps:
Create a directory structure for the theme in the /usr/share/themes directory. Use the same directory structure that other themes use. For example, to create a theme that is called SmallPrint, create the following directories:
Locate the gtkrc theme file that is closest to meeting the needs of your users. Copy the file to the gtk-2.0 directory of your new theme.
Open the gtkrc file in a text editor, and modify the attributes of the interface elements as required.
If the new theme includes images, install the images for the new theme in the pixmaps directory of your new theme. If the new theme uses images from another theme, you do not need to create copies of the images for the new theme. Instead, ensure that the reference to the images in the pixmap_path entry in the gtkrc file is correct.
Users can now choose the new theme.
For more information on gtkrc files, see http://developer.gnome.org/doc/API/2.0/gtk/index.html.