Magento 1 - Add comment blocks to html output to debug layout & blocks.

Magento 1 - Layout-Block Debug.php

<?php

/** 
 * Modify
 * File : app/code/core/Mage/Core/Block/Template.php
 * Method: fetchView
 *         At the very begining.
 * 
 */
$startTime = microtime(true);

/** 
 * Modify
 * File : app/code/core/Mage/Core/Block/Template.php
 * Method: fetchView
 *         At the end replace the return.
 * 
 */
$block = get_class($this);
$tags = implode(',', $this->getCacheTags());
$key = $this->getCacheKey();
$time = date(DATE_ISO8601);
$genTime = microtime(true) - $startTime;
$debug = "<!-- ";
$debug .= "\n\t- Block: $block";
$debug .= "\n\t- name: {$this->getNameInLayout()}";
$debug .= "\n\t- template: $includeFilePath";
$debug .= "\n\t- date: $time";
$debug .= "\n\t- cache-key: $key";
$debug .= "\n\t- cache-lifetime: " . $this->getCacheLifetime();
$debug .= "\n\t- cache-tags: $tags";
$debug .= "\n\t- cache-ttl: {$this->getCacheLifetime()}";
$debug .= "\n\t- gen-time: $genTime";
$debug .= "-->";

return $debug . $html;