_removeButton() method not working

Question

This should be so simple, but _removeButton() method is not working.

class Thing_MyModule_Block_Adminhtml_Foo 
        extends Mage_Adminhtml_Block_Widget_Grid_Container {

    public function _construct() {
        $this->_controller = 'adminhtml_mymodule';
        $this->_blockGroup = 'mymodule';
        $this->_headerText = Mage::helper('mymodule')->__('Hello There');
        parent::_construct();
        $this->_removeButton('add'); // does not work
    }

}

Needless to say I'm missing something obvious and the "+ Add New" button is still there. Yes, I have tried it before and after the call to parent::_construct();

If I do var_dump($this->_buttons); I get

array (size=3)
  -1 => 
    array (size=0)
      empty
  0 => 
    array (size=0)
      empty
  1 => 
    array (size=0)
      empty

...which makes no sense to me. AM LOSING MY MIND! Please help!

Magento ver. 1.8.1.0

Answer 1

Solved. Rather than calling _removeButton() in _construct(), calling it in _prepareLayout() works just fine.

class Thing_MyModule_Block_Adminhtml_Foo 
    extends Mage_Adminhtml_Block_Widget_Grid_Container {

    public function _construct() {
        $this->_controller = 'adminhtml_mymodule';
        $this->_blockGroup = 'mymodule';
        $this->_headerText = Mage::helper('mymodule')->__('Hello There');
        parent::_construct();
        $this->_removeButton('add');  // this does not work
    }

    protected function _prepareLayout() {
        $this->_removeButton('add');  // this is just dandy
        return parent::_prepareLayout();
    }

    ...