Using a tag like {content block='my_block' block_type='select_multiple'
items=':::my_plugin_or_udt:::' smarty='backend' label='Some stuff'} in a multi
input template fails the content edit page. A fatal error "Call to a member
function Id() on a non-object in
**/modules/AdvancedContent/lib/class.ac_utils.php on line 148" appears.

To fix this issue, change in class.acBlockType_multi_input.php line 41:
$inputBlock->SetProperty($propName, ac_utils::DoSmarty($content_obj,
$propValue));
into:
$inputBlock->SetProperty($propName, ac_utils::DoSmarty($this->content_obj,
$propValue));