In Symphony 2.2.1 you get the dark side of the force to customize some particular views, like Exceptions and Fatal Error templates.
We're going to learn what each template do, and how we can customize them. All described files here are located in the symphony/template directory.
datasource.tpl represents Data Sources created in the back-end. There is not much you can do but you can get rid of some useless data in the about() function like website.
event.tpl same as Data Sources, but for events.
errorhandler.tpl handles any uncaught exceptions thrown in Symphony. See more.
fatalerror.tpl displays the Exception message as provided by the Database. See more.
page.xsl copied and pasted to your workspace when you create a new page in the back-end.
tpl.database-error.php See more.
Remember that editing these files isn't considered hacking the core.