Contextual wrapper missing when using modul_invoke and theme_block function through preprocess_page

Hi there.
beforehand, i have to say that its a really great work u did.

One issue i cannot handle with is when i don't want to show/enable blocks through regions, but to call them programmatically e.g. in page-front.tpl.php template through preprocess_page function where i have similar code to this one below:

$block = (object) module_invoke('block', 'block', 'view', $deltanum);
$block->subject = 'Example block';
$block->module = 'block';
$block->delta = $deltanum;
$vars['example_block_var'] = theme('block', $block);

The problem is that the contextual-wrapper with links is not rendered. I guess that i need to add some extra variables, or just to call different theme function, but i cannot find where the problem is.

Pls, can u kick off my brain? Thanks a lot for any response.