     })
 
     # make container
-    container = $('<div id=container></div>').css({
+    @container = $('<div id=container></div>').css({
         position: 'absolute'
         top: (@here.height - @above.height + 71) / 2
         left: (@here.width - @above.width + 71) / 2
     })
-    frame.append(container)
+    frame.append(@container)
 
     # make invisible grid on which the pawn moves
     grid = $('<div id=grid></div>').css({


  destroy: ->
    $(document).off('keyup')

  whenIdle: (callback) =>
    @queue.push(callback)

            context.lineWidth = 2
            context.stroke()
      @floors[z] = floor
      @container.append(floor)
      floor.css({
          position: 'absolute'
      })
