code: public boolean hasAccess(final TargetMode _targetMode,
                               final Instance _instance)
          throws EFapsException
      {
          return hasAccess(_targetMode, _instance, null, null);
      }
docs: Check, if the user of the context has access to this user interface
  object. <br>
  The Check is made in the following order: <br>
  <ol>
  <li>If no access User or role is assigned to this user interface object,
  all user have access and the return is <i>true</i> => go on with Step 3</li>
  <li>else check if the context person is assigned to one of the user
  objects.</li>
  <li>if Step 1 or Step 2 have <i>true</i> and the context an Event of the
  Type <code>TriggerEvent.ACCESSCHECK</code>, the return of the trigger
  initiated program is returned</li>
  </ol>
  
  @param _targetMode targetmode of the access
  @param _instance the field will represent, e.g. on edit mode
  @return <i>true</i> if context user has access, otherwise <i>false</i> is
  returned
  @throws EFapsException on error