Properties And Atoms

Properties and atoms provide a method of inter-client communication and data transfer. A property is a packet of information belonging to a window. The information is stored in the server and made available to all clients running on the server. Properties have names such as WM_HINTS, which can be translated by the Xlib routine XInternAtom in to an ID called an atom. Clients can then refer to properties using an atom rather than an arbitrary length string name. Of course a property name and the corresponding atom refer to a particular type of property of which several windows may have an instance. So, in order to uniquely identify a particular property for a particular window, a client must specify an atom and a window ID.

One important use of properties is communication between clients and the window manager, which is itself a client. Information regarding the preferred size and location etc. of a clients main window can be passed to the window manager in this way. Such properties are known as standard properties.