         console.log "WARN: unable to run LightBox#findSubjectIndex"
 
   moveBack: (indexOfFirst)->
+    return null if @props.subject_set.subjects[indexOfFirst] == @props.subject_set.subjects[0]
     @setState
       first: @props.subject_set.subjects[indexOfFirst-1]
 
   moveForward: (indexOfFirst)->
+    return null if @props.subject_set.subjects[indexOfFirst+2] == @props.subject_set.subjects[@props.subject_set.subjects.length-1]
     @setState
       first: @props.subject_set.subjects[indexOfFirst+1]
     

    viewBox = [0, 0, 100, 100]
    <div className="carousel">

      <ActionButton text="UP" onClick={@moveBack.bind(this, indexOfFirst)} classes={if @state.first == @props.subject_set.subjects[0] then 'disabled' else ''}/>

      <ul>
        <li onClick={@shineSelected.bind(this, @findSubjectIndex(@state.first))}> 

  propTypes:
    subject_set: React.PropTypes.object.isRequired
    subject_index: React.PropTypes.number.isRequired
    onSubject: React.PropTypes.func.isRequired

  getInitialState:->
    first: @props.subject_set.subjects[@props.subject_index]


  shineSelected: (index)->
