A method and system modifies a user interface of a portable device in communication with an interface device, where the UI is projected by a human-machine interface of the interface device to a user. The unheated roller shell is secured in the hair without risk of heating or burning the skin. The controller has a desired angular difference setting means which variably sets the desired value of the angular difference according to at least a required condition related to a movement mode of the object. The free edge of the pocket panel is disposed next to the secured edge and extends transversely of the secured edge.