code: function ProblemService(serviceRegistry, serviceID) {
  		this._serviceRegistry = serviceRegistry;
  		EventTarget.attach(this);
  		this._serviceRegistration = serviceRegistry.registerService(serviceID || "orion.core.marker", this); //$NON-NLS-0$
  	}
docs: Creates a new problem service instance. Client should obtain the service
  <tt>orion.core.marker</tt> from the service registry rather than instantiate
  this service directly.
  @class The problem service tracks markers and sends notification of marker changes.
  @name orion.problems.ProblemService