app/code/community/Aoe/TemplateHints/Model/Observer.php
public function getRenderer() {
        if (is_null($this->renderer)) {
            $rendererClass = Mage::getStoreConfig('dev/aoe_templatehints/templateHintRenderer');
            if (empty($rendererClass)) {
                Mage::throwException('No renderer configured');
            }
            $this->renderer = Mage::getSingleton($rendererClass);
            if (!is_object($this->renderer) || !$this->renderer instanceof Aoe_TemplateHints_Model_Renderer_Abstract) {
                Mage::throwException('Render must be an instanceof Aoe_TemplateHints_Model_Renderer_Abstract');
            }
        }
        return $this->renderer;
    }
public function getRenderer() {
        if (is_null($this->renderer)) {
            $rendererClass = Mage::getStoreConfig('dev/aoe_templatehints/templateHintRenderer');
            if (empty($rendererClass)) {
                Mage::throwException('No renderer configured');
            }
            $this->renderer = Mage::getSingleton($rendererClass);
            if (!is_object($this->renderer) || !$this->renderer instanceof Aoe_TemplateHints_Model_Renderer_Abstract) {
                Mage::throwException('Render must be an instanceof Aoe_TemplateHints_Model_Renderer_Abstract');
            }
        }
        return $this->renderer;
    }
Get renderer

@return Aoe_TemplateHints_Model_Renderer_Abstract