features of the OS, including a camera which is able to rewind frame-by-frame separately of individual faces in an image, to allow selection of the best of different shots, which is then stitched seamlessly to an optimal composite, an intelligent, predictive, and adapting keyboard, and a gesture based user interface designed around the idea of "peek" and "flow". Apps are available for BlackBerry 10 devices through the BlackBerry World storefront. The previous operating system developed for older BlackBerry devices was BlackBerry OS, a proprietary multitasking environment developed by RIM. The operating system is designed for use of input devices such as the track wheel, track ball, and track pad. The OS provides support for Java MIDP 1.0 and WAP 1.2. Previous versions allowed wireless synchronisation with Microsoft Exchange Server email and calendar, as well as with Lotus Domino email. OS 5.0 provides a subset of MIDP 2.0, and allows complete wireless activation and synchronisation with Exchange email, calendar, tasks, notes and contacts, and adds support for Novell GroupWise and Lotus Notes. The BlackBerry Curve 9360, BlackBerry Torch 9810, Bold 9900/9930, Curve 9310/9320 and Torch 9850/9860 featured the 2011 BlackBerry OS 7. Apps are available for these devices through BlackBerry World (which before 2013 was called BlackBerry App World). Third-party developers can write software using these APIs, and proprietary BlackBerry APIs as well. Any application that makes use of certain restricted functionality must be digitally signed so that it can be associated to a developer account at RIM. This signing procedure guarantees the authorship of an application but does not guarantee the quality or security of the code. RIM provides tools for developing applications and themes for BlackBerry. Applications and themes can be loaded onto BlackBerry devices through BlackBerry World, Over The Air (OTA) through the BlackBerry mobile browser, or through BlackBerry Desktop Manager. BlackBerry devices, as well as Android, iOS, and Windows Phone platforms, have the ability to use the proprietary BlackBerry Messenger, also known as BBM, software for sending and receiving encrypted instant messages, voice notes, images and videos via BlackBerry PIN. As long as your cell phone has a data plan these messages are all free of charge. Some of the features of BBM include groups, bar-code scanning, lists, shared calendars, BBM Music and integration with apps and games using the BBM social platform. In April 2013, BlackBerry announced that it was shutting down its streaming music service,