Alan Cooper

to minimize mouse movement

Mobile platforms have done a good job of collecting notifications into notification centers, which permit viewing of notifications after the fact: Users might be unable to address a message or triggered alarm until they have stopped driving, taken a seat on the bus they were catching, or finished a phone call they were in.

Bulletin dialogs normally are application-modal: They stop all further progress of the application until the user issues a terminating command—like tapping the OK button. This type of bulletin is blocking because the application cannot continue until the user responds.