Allowing Interruptions

Users sometimes need to stop a command— for example, because it is taking too long. Your application should let users stop commands in progress, even if stopping a command cannot undo or "roll back" all the command's effects.

Guidelines

Alternatively, you can place the Stop or Cancel button near the control with which the user issued the command that needs to be stopped. Place the button here only if:

In the alert box that appears after pressing a Stop button, ensure the message and button labels in the alert box are specific and precise. Ambiguous button labels can cause users to terminate or continue a command unintentionally. For example, use:

Continue deleting files? [Continue Deleting]
    [Stop Deleting]

rather than

Operation interrupted, continue? [Yes]
    [No]

since in the latter example, it is not clear whether pressing Yes would continue the operation or continue the interruption (i.e. cancel the operation).