If not using a table prefix with SQlite, $table_prefix is empty, resulting in the following error when trying to view the database backup page:

PHP Notice: in file /includes/acp/acp_database.php on line 1054: strpos() [function.strpos]: Empty delimiter.

Suggested fix: replace line 1054 of acp_database.php with

if (empty($table_prefix) || strpos($row['name'], $table_prefix) === 0)

Or (because empty() considers the string '0' to be empty)

if (strlen($table_prefix) == 0 || strpos($row['name'], $table_prefix) === 0)

Thanks, Eli