lib/metro/events/event_relay.rb
def fire_events_for_held_buttons
      held_actions.each do |key,action|
        execute_block_for_target(&action) if window and window.button_down?(key)
      end
    end
def fire_events_for_held_buttons
      held_actions.each do |key,action|
        execute_block_for_target(&action) if window and window.button_down?(key)
      end
    end
Fire the events mapped to the held buttons within the context
 of the specified target. This method is differently formatted because held buttons are not
 events but polling to see if the button is still being held.