def add_mouse_event_listener
      Element.find("##{@canvas.id}").on :mousemove do |event|
        coords = get_cursor_position(event)
        @mouse_x = coords.x[:x]
        @mouse_y = coords.x[:y]
      end
    end
def add_mouse_event_listener
      Element.find("##{@canvas.id}").on :mousemove do |event|
        coords = get_cursor_position(event)
        @mouse_x = coords.x[:x]
        @mouse_y = coords.x[:y]
      end
    end
adds mousemove event listener to main canvas