However, if they develop their own widgets, they will have to ensure that they are exposing all the accessible information. Developers who use stock widgets of GUI toolkits that implements the ATK headers can more easily make their applications accessible. The ATK abstract headers files are freely available to help developers who want to make their GUI toolkit accessible.

In the case of GNOME, there are two different APIs, one for the client-side ( Assistive Technology Service Provider Interface (AT-SPI)) and a different one for the server-side (ATK) due to historical reasons related to the underlying technologies. Usually the API for both client-side and server-side applications are the same, and the accessibility framework provides a client-side and a server-side implementation of that API. Ideally the accessibility framework expose this to the client and server in a transparent way. In this architecture the client and server need to communicate with each other, usually using the IPC technology of the platform. In that way, assistive technologies (ATs) such as screen readers, would be the clients of that framework, and computer applications would be the server. One common nomenclature to explain an accessibility framework is a usual client-server architecture. Pango, GDK, ATK, GIO, Cairo and GLibĪccessibility Toolkit ( ATK) is an open source software library, part of the GNOME project, which provides application programming interfaces (APIs) for implementing accessibility support in software.

Simplified software architecture of GTK+.

Qt toolkit accessibility screen reader