window_example.cr

class Boleite::GUI
  class Window < Container
    # ...

    Cute.signal header_drag(pos : Vector2f)

    def initialize
      # ...

      state_change.on &->update_header_size
      header_drag.on &->move(Vector2f)
      @input.register_instance WindowHeaderDrag.new(self), header_drag
    end
    
    # ...
  end
end