   for prefix in prefixList
     hyphenated = "-#{ prefix.toLowerCase() }-linear-gradient"
     testEl.style.backgroundImage = "#{ hyphenated }(left, #000, #fff)"
-    if testEl.style.backgroundImage.indexOf('gradient') isnt -1
+    unless testEl.style.backgroundImage.indexOf('gradient') is -1
       return hyphenated
   'linear-gradient'
 

        setTimeout =>

          unless i is limit
            do (j = i) =>
              setTimeout =>
                @panels[anchor][j].style.display = 'none'
              , delay * .8

          @panels[anchor][i].style[css.transform] = @_transform angle



  unfold: (callback) ->
    unless @isFoldedUp
      if typeof callback is 'function'
        callback()

