[XP Script] Prevent Deactivation

The version for Ruby 1.8+
Code:
=begin

================================================================================

 Prevent Deactivation

 Author: KK20

 Version: 1.1

--------------------------------------------------------------------------------

 [ Description ]

 When the game window is no longer the active window, it normally freezes the

 game from updating. This script will allow games to still run in the background.

 [ Instructions ]

 You can enable / disable this feature in-game using the script call:

              $game_system.keep_game_active = true / false

 This is useful for custom menu options so that the player can choose their

 preference of whether the game runs in the background or not.

 Script should be placed as low as possible in your script list, but still

 above Main.

 It is highly advised to not modify this script unless you know what you are

 doing.

================================================================================

=end

module MessageIntercept

  Start = Win32API.new('MessageIntercept', 'Init_Deactivate', 'pp', 'i')

  Toggle = Win32API.new('MessageIntercept', 'KeepGameActive', 'i', '')

  Flag_Deactivate = [1].pack('C*')

end

module Input

  class << self

    if @intercept_f12_stack.nil?

      alias update_if_game_in_focus update

      @intercept_f12_stack = true

    end

  end

  # Only accept player input if the game window is in focus

  def self.update

    update_if_game_in_focus if MessageIntercept::Flag_Deactivate[0] == 1

  end

end

class Game_System

  attr_reader :keep_game_active

  alias init_for_no_deactivate initialize

  def initialize

    @keep_game_active = true

    init_for_no_deactivate

  end

  # When loading a save, need to make DLL call to enable/disable keeping the

  # game active

  alias original_update_no_deactivate update

  def self.modify_update(revert = false)

    if revert

      alias update original_update_no_deactivate

    else

      alias update no_deactivate_update

    end

  end

  def no_deactivate_update

    MessageIntercept::Toggle.call(@keep_game_active ? 1 : 0)

    original_update_no_deactivate

    Game_System.modify_update(true)

  end

  def keep_game_active=(bool)

    @keep_game_active = bool

    MessageIntercept::Toggle.call(@keep_game_active ? 1 : 0)

  end

end

class Game_Temp

  alias change_gamesystem_update_init initialize

  def initialize

    change_gamesystem_update_init

    Game_System.modify_update

  end

end

if MessageIntercept::Start.call('.\\Game.ini', MessageIntercept::Flag_Deactivate) == -1

  raise 'ERROR: Prevent Deactivation failed to set new window procedure!'

end