How do I check if a block region is empty?
An update on this. I used the solution at https://drupal.stackexchange.com/a/73685/56728 as follows

  module_load_include('inc', 'block', 'block.admin');
  global $theme_key;
  $blocks = block_admin_display_prepare_blocks($theme_key);
  //test for a named block's (here the help block) visibility
  foreach($blocks as $block){
    if($block['delta'] == 'help' &amp;&amp; $block['region'] != -1){
      sdpm($block['delta']. " is visible!");
    }
  }


This detects whether the block is visible or not, but does not quite do what I'm after which is to test for the visibility of a given block on the current "page" for the current user. That to me sounds like what block_list() does, but I'm stumped by block_list() as I mentioned above. My "solution" also very likely not the most elegant way of doing things so any help from experts out there would be greatly appreciated. Nat