mode, and gets an undesired response. A mode error can be startling, disorienting and annoying as the user copes with the violation of their expectations.

Problems occur if a change in the system state happens unnoticed (initiated accidentally, by the system, or by another person), or if after some time the user forgets the current mode. Another common problem is a sudden change of state that interrupts a user's activity, such as focus stealing. In such a situation it the may perform operations