$form['googleanalytics_custom_var']['slots'][$i]['value'] = array(
'#default_value' => !empty($googleanalytics_custom_vars['slots'][$i]['value']) ? $googleanalytics_custom_vars['slots'][$i]['value'] : '',
'#description' => t('The custom variable value. You may use tokens in this field.'),
+ '#maxlength' => 255,
'#title' => t('Custom variable value #@slot', array('@slot' => $i)),
'#title_display' => 'invisible',
'#type' => 'textfield',