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


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

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

    })

    # make container
    @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)

    # make invisible grid on which the pawn moves
    grid = $('<div id=grid></div>').css({
