function openLink (oEvent) {
		if (oEvent.originalEvent.defaultPrevented) {
			return;
		}
		oEvent.preventDefault();
		openWindow(oEvent.currentTarget.href, oEvent.currentTarget.target);
	}
Sets the contrast class on the ActionSheet's Popover based on the current theme.

@param {sap.ui.base.Event} event The 'beforeOpen' event
@private