Window frame themes reside in the /usr/share/themes/theme_name/metacity-1 directory. The typical structure of a window frame theme in the file system is as follows:
Typically, a new window frame theme is supplied as a .tar.gz file. To install the new window frame theme, unzip the .tar.gz file, then untar the .tar file into the /usr/share/themes directory.
Users can install their own window frame themes. If a user installs a window frame theme, the theme is stored in the $HOME/.themes directory.