An embodiment relates to a system for scrambling characters of a password entered by a user on an input device. Thus, the adjusting unit is hidden in a space between the first side rack and the second side rack, so that the adjusting unit is not operated unintentionally. Upon receiving a notification of an event, the event sink forwards the notification to any registered listeners. In one embodiment, the flexible portion is itself of a thickness of at least about 3 mm, and the cut-out portion forms an opening in the flexible portion.