How to use QuickLook in Macruby

application.rb

require 'rubygems' # disable this for a deployed application
require 'hotcocoa' 
framework 'Quartz'
       
# This Needs to conformal to QLPreviewItem 
class Item  
  attr_accessor :previewItemURL
end    

module QLookBehaviors  
  attr_accessor :item
    
  def acceptsPreviewPanelControl(panel)
    return true 
  end   
  
  def beginPreviewPanelControl(panel)
    panel.delegate   = self
    panel.dataSource = self 
  end

  def endPreviewPanelControl(panel) 
    @previewPanel = nil
  end

  def numberOfPreviewItemsInPreviewPanel(panel) 
    return 1
  end

  def previewPanel(panel, previewItemAtIndex:index)
    return @item
  end
  
  def togglePreviewPanel() 
    if QLPreviewPanel.sharedPreviewPanelExists && QLPreviewPanel.sharedPreviewPanel.isVisible
      QLPreviewPanel.sharedPreviewPanel.orderOut(nil)
    else 
      QLPreviewPanel.sharedPreviewPanel.makeKeyAndOrderFront(self)
    end
  end
end       

class RQuicklook
  include HotCocoa

  def start          
    application name: 'RQuicklook' do |app| 
      app.delegate = self 
      
      @main_window = window(:frame => [100, 100, 600, 500], :title => "HotCocoa Demo Application") do |win| 
        win.will_close { exit } 
        win.extend(QLookBehaviors)  
        win.item = Item.new
        win.item.previewItemURL = NSURL.alloc.initFileURLWithPath('filepath')  
        win.togglePreviewPanel()
      end 
    end
  end  
end

RQuicklook.new.start