frames-on-display-list

frames-on-display-list is a compiled Lisp function in `frame.el'.

(frames-on-display-list &optional DEVICE)

Return a list of all frames on DEVICE.

DEVICE should be a terminal, a frame,
or a name of an X display or tty (a string of the form
HOST:SERVER.SCREEN).

If DEVICE is omitted or nil, it defaults to the selected
frame's terminal device.