In Boost's config.php file there are layout options, such as on the 'mydashboard' layout:

'options' => array('nonavbar' => true, 'langmenu' => true),

these are ignored as in this example, the navbar is shown on the page, and for the 'mycourses' layout, which only has:

'options' => array('nonavbar' => true),

then the language menu is still a user menu item (its new place in M4.0).