function _hasAsRealChild(oParent, oChild) {
		return !oChild.aAPIParentInfos || oChild.aAPIParentInfos[0].parent === oParent;
	}
Calls a registered listener during propagation

@param {function} listener
     If given, the given function will be called, other wise all propagation listeners will be called.
@returns {this} Returns <code>this</code> to allow method chaining
@private