XLIB Programming Manual, Rel. 5, Third Edition

F.13 Display Queue Functions

XmuDQCreate creates and returns an empty XmuDisplayQueue (which is really just a linked list of displays; it is called a queue for historical reasons). The queue is initially empty, but displays can be added using XmuDQAddDisplay. Functions can be added for each display, to be called when the display connection is closed. These are called close callbacks. Functions can also be added to be called when the last display connection is closed. These are called free callbacks. The application is responsible for actually freeing the queue, by calling XmuDQDestroy.

XmuDQAddDisplay does not attempt to prevent duplicate entries in the queue; the caller should use XmuDQLookupDisplay to determine if a display has already been added to a queue. The XmuDQNDisplays macro returns the number of displays in the specified queue. XmuDQRemoveDisplay removes the specified display from the specified queue, without calling its close callbacks. XmuDQDestroy releases all memory associated with the specified queue and optionally calls the close callbacks for each display.