Flash MX 2004.
layer.locked
Property; a Boolean value that specifies the locked status of the layer. If set to true, the layer is locked. The default value is false.
The following example stores the Boolean value for the status of the first layer in the lockStatus variable:
var lockStatus = fl.getDocumentDOM().getTimeline().layers[0].locked;The following example sets the status of the first layer to unlocked:
fl.getDocumentDOM().getTimeline().layers[0].locked = false;