Hi,
Yes...if you open ../theme/zebra/config.php using Notepad, you will see in the theme layout section under login a bit of code relating to options and lang. Copy that line of code to all the layout sections listed. It should look something like this...so by copying the section highlighted in green and overwriting the empty options, which is written in red here...you will get the lang menu to work in every page, providing you have that option enabled in Moodle.
'mypublic' => array(
'file' => 'general.php',
'regions' => array('side-pre', 'side-post'),
'defaultregion' => 'side-pre',
'options' => array()
),
'login' => array(
'file' => 'general.php',
'regions' => array(),
'options' => array('langmenu'=>true)
),