fnOnItemSelect = function(oEvent) {
			// Emulate an event-object to "trick" the Shell into believing a real panel
			// item was selected
			var mPseudoEvent = {
				overflowItem : oEvent.getParameter("item"),
				target : {
					id : oEvent.getParameter("id").replace(/-overflow$/, ""),
					parentNode : {
						className : "sapUiUx3ShellPaneEntries"
					}
				}
			};

			that.onUserActivation(mPseudoEvent);
		}
This sets a NotificationBar to the Shell. If there is a NotificationBar
attached already the old one will be removed. Additionally the Shell attaches
itself to the NotificationBar's <code>display</code>-event.

@param {object} oNotificationBar is the NotificationBar that should be
attached to the Shell
@return {object} this to enable chaining of setters and getters