I am using plugin 0.7-beta4 on WP 3.5.
I get the following error on a menu widget which uses "Current page's top parent" as starting menu:
Warning: Invalid argument supplied for foreach() in /home/xxxxx/public_html/wp-content/plugins/gecka-submenu/models/NavMenuHacks.php on line 94
I fixed this by myself, hacking the plugin source code, by adding a check like
if (is_array($items)), but I hope it will be fixed in next releases.