   events: ->
     if ENV.mobile
       events =
-        'touchend .back': 'back' 
+        'touchend .back': 'back'
         'touchend .previous': 'previous'
         'touchend .next': 'next'
         'touchend .play': 'play'
         'touchend canvas': 'select'
     else
       events =
-        'click .back': 'back' 
+        'click .back': 'back'
         'click .previous': 'previous'
         'click .next': 'next'
         'click .play': 'play'

    # Determine the last viewed level for this difficulty
    @selectedLevel = localStorage.getObject('lastViewedLevel')[@difficulty] || 0
    @page = Math.floor(@selectedLevel / @perPage)
    
    # disable/enable buttons
    @$('.previous, .next').addClass 'disabled'
    if @page > 0 then @$('.previous').removeClass 'disabled'

  back: (e) ->
    e.preventDefault()
    @undelegateEvents() # Prevent multiple clicks

    @trigger 'sfx:play', 'button'
    @trigger 'scene:change', 'difficulty'

