el = LISTENER(hSource, Eventname, callbackFcn) creates a listener
for the event named Eventname.  The source of the event is the handle  
object hSource.  If hSource is an array of source handles, the listener
responds to the named event on any handle in the array.  callbackFcn
is a function handle that is invoked when the event is triggered.
el = LISTENER(hSource, PropName, Eventname, callback) adds a 
listener for a property event.  Eventname must be one of  
'PreGet', 'PostGet', 'PreSet', or 'PostSet'. Eventname can be a 
string sclar or character vector.  PropName must be either a single 
property name specified as a string scalar or character vector, or 
a collection of property names specified as a cell array of character 
vectors or a string array, or as an array of one ore more 
meta.property objects. The properties must belong to the class of 
hSource.  If hSource is scalar, PropName can include dynamic 

For all forms, listener returns an event.listener.  To remove a
listener, delete the object returned by listener.  For example,
delete(el) calls the handle class delete method to remove the listener
and delete it from the workspace.  Calling delete(el) on the listener
object deletes the listener, which means the event no longer causes
the callback function to execute. 
LISTENER does not bind the listener's lifecycle to the object that is
the source of the event.  Destroying the source object does not impact
the lifecycle of the listener object.  A listener created with LISTENER
must be destroyed independently of the source object.  Calling 
delete(el) explicitly destroys the listener. Redefining or clearing 
the variable containing the listener can delete the listener if no 
other references to it exist.  To tie the lifecycle of the listener to 
the lifecycle of the source object, use addlistener.
See also ADDLISTENER, EVENT.LISTENER, SPINW, NOTIFY, DELETE, META.PROPERTY, EVENTS Help for spinw/listener is inherited from superclass HANDLE
Reference page in Doc Center
   doc spinw/listener