There is no automated tool for the identification of the various themeable functions in Drupal. You can, however, identify them by their names, because all themeable functions employ a consistent naming convention. Themeable functions' names all begin with theme_ and they are located in the modules and includes directories. The naming convention makes it possible to work your way through the various files to isolate all the functions. You can ease the pain somewhat by setting up Dreamweaver or a similar program to do the searching for you.

Additionally, you can use the following snippet of PHP code from within Drupal to produce a list of the active functions on your installation.

<?phpprint '<ol>';
$functions = get_defined_functions();
foreach($functions['user'] as $function) {
if(substr($function,0,6)== 'theme_')
print "<li>$function</li>";
}
print '</ol>';
?>

To use this code, first create a new Block within your site. Set the...