Widget engines speed work by keeping commonly used widgets accessible while unobtrusive. SoundCloud distributes music using widgets and apps. This includes support for predelivery, RSS feeds, web widgets, and JavaScript applications. The GUI uses the GTK+ toolkit and Hildon user interface widgets and API. It supports buttons, menus, sliders, tabs and other basic GUI widgets. The browser integrated widgets such as social networking, chat clients and email facilities. Other features include embeddable widgets and bookmarklets. It also encapsulates AJAX functionality and has a broad selection of UI widgets. It ships with an enhanced set of UI widgets, both for Windows Forms and WPF. It uses GTK+ for its GUI widgets. The W3C is creating a set of standards for web widgets. Fios TV's video on demand and interactive widgets use Internet Protocol technology. GSK lies between the graphical control elements (widgets) and the rendering. The Flutter framework contains two sets of widgets which conform to specific design languages. Nine interactive "widgets" were included with iWeb.