Magento Observer for Product/Orders Massactions

config.xml

 <events>
  <core_block_abstract_prepare_layout_before>
    <observers>
      <massaction_observers>
        <type>singleton</type>
        <class>My_Awesome_Observer</class>
        <method>addMassAction</method>
      </massaction_observers>
    </observers>
  </core_block_abstract_prepare_layout_before>
</events>

Observer.php

public function addMassAction($observer) {
  $block = $observer->getEvent()->getBlock();
  if(!$block) {
    return $this;
  }
  
  $store = Mage::app()->getStore();
  $storeId = Mage::app()->getStore()->getCode();
  
  if($block instanceof Mage_Adminhtml_Block_Widget_Grid_Massaction) {
    if($block->getRequest()->getControllerName() == 'sales_order') {
      $block->addItem(
        'pdfs',
        array('label' => Mage::helper('adminhtml')->__('+ Print PDF Picking List'),
          'url' => Mage::app()->getStore()->getUrl('*/pdfgen/generatePdfs')
        )
      );
    }
  }
}