Windows Mobile 6.1 was announced April 1, 2008. It is a minor upgrade to the existing Windows Mobile 6 platform which brings with it various performance enhancements, a redesigned Home screen featuring horizontal tiles that expand on clicking to display more information, although this new home screen is featured only on Windows Mobile Standard edition. This feature was inexplicably left out of the Professional edition. Several other improvements such as threaded SMS, full page zooming in IE and 'Domain Enroll' have also been added, along with a "mobile" version of the Microsoft OneNote program and an interactive "Getting Started" wizard.