This feature is not on a current W3C standards track, but it is supported on the Firefox OS platform. Although implementations may change in the future and it is not supported widely across browsers, it is suitable for use in code dedicated to Firefox OS apps.
closed property indicates whether or not the settings lock is closed.
var isClosed = instanceOfSettingsLock.
Returns a Boolean indicating the state of the settings lock; if
true, the lock is no longer active. If
false, the lock is still the active lock.
Not part of any specification yet; however, this API will be discussed at W3C as part of the System Applications Working Group.