How do I restore a windows size and position in a wxRuby app?

Does anyone know of any sample code for restoring a window's position and size in wxRuby?

YAML would be a better choice to serialize the prefs, but here I just store a comma-delimited string in the prefs.txt file.

require "rubygems"
require "wx"
include Wx

class MyApp < App
  def on_init
    left, top, width, height = *prefs
    position = Point.new(left, top)
    size = Size.new(width, height)
    main = Frame.new(nil, -1, "Title", position, size)

    #when the window closes, save the location
    main.evt_close do |event|
      save_window_location(event.get_event_object)
      event.skip
    end
    main.show()
  end

  private

  def save_window_location(frame)
    self.prefs = [
      frame.position.x,
      frame.position.y,
      frame.size.width,
      frame.size.height
    ]
  end

  #load the prefs and return them as an array
  def prefs
    location = []
    begin
      location = File.read(prefs_filename).split(',').map{|s| s.to_i}
    rescue Exception
      #file didn't exist, or read failed
    end
    location = [100, 100, 300, 300] if location.size != 4
    return location
  end

  #save the prefs as a comma-delimited string
  def prefs=(prefs_array)
    File.open(prefs_filename, 'w') do |prefs_file|
      prefs_file << prefs_array.join(",")
    end
  end

  def prefs_filename
    'prefs.txt'
  end
end

MyApp.new.main_loop