This interface provides a means to cancel an operation that is in progress.

 @status UNDER_REVIEW
[scriptable, uuid(d94ac0a0-bb18-46b8-844e-84159064b0bd)]
interface nsICancelable : nsISupports

Methods

 Call this method to request that this object abort whatever operation it
 may be performing.

 @param aReason
        Pass a failure code to indicate the reason why this operation is
        being canceled.  It is an error to pass a success code.
void cancel(in nsresult aReason)