# File lib/rubygame/surface.rb, line 581
  def to_display_alpha
    newsurf =
      if( Rubygame.init_video_system() == 0 )
        SDL.DisplayFormatAlpha( @struct )
      else
        nil
      end

    if( newsurf.nil? or newsurf.pointer.null?)
      raise( Rubygame::SDLError,
             "Could not convert the Surface to display format "+
             "with alpha channel: #{SDL.GetError()}" )
    end

    # Wrap it
    return self.class.new( newsurf )
  end