Example for GKing

class Scene_Map < Scene_Base

  alias :ex_start :start
  def start
    ex_start
    @infos = My_Window.new(0, 0, 200, 100)
  end

  alias new_update update
  def update
    new_update
    change_character if Input.trigger?(:C)
  end

  def change_character
    Sound.play_ok
    $game_party.swap_order($game_party.leader.index, $game_party.members[1].index)
    @infos.refresh
  end

end

class My_Window < Window_Base

  def initialize(x, y, width, height)
    super(x, y, width, height)
    self.opacity = 50
  end

  def update
    super
    @actor1 = $game_party.leader
    if @actor1.hp != @hp || @actor1.mp != @mp
      refresh
    end
  end

  def refresh
    self.contents.clear
    self.draw_character(@actor1.character_name, @actor1.character_index, 16, 32)
    self.draw_actor_hp(@actor1, 42, 16)
    self.draw_actor_mp(@actor1, 42, 42)
    @hp = @actor1.hp
    @mp = @actor1.mp
  end

end