addPanel = ->
    ix = Utils.round((Math.random() * ((numColumns * numRows) - 1)), 0)
    if panels[ix]?
        panels[ix].destroy()
    panels[ix] = new Layer
        width:panelWidth
        height:panelHeight
        x: (ix % numColumns) * panelWidth
        y: (0 | ix / numRows) * panelHeight