The Theme Preferences file (theme_preferences.php) file is used as part of the installation process to activate or configure aspects of ExpressionEngine 2.x for use in the theme that is being installed.
Parameters include:
$default_group = ‘x’;
x would be the template group that you want to be set as default. An example would be:
$default_group = ‘site’;
In this case the Template Group site would be used as the default. Visitors to yoursite.com would be fed the index template in this template group.
$required_modules = array(‘x’, ‘y’, ‘z’);
where x, y and z represent modules that are installed and required for the template to work. An example would be:
$required_modules = array(‘email’, ‘rss’, ‘comment’, ‘search’);
Note: There is a Themes Manual EE 2.0 started to collect information about theme development. Please contribute if you have information.