frameset-switch-to-tty-p
frameset-switch-to-tty-p is a compiled Lisp function in `frameset.el
'.
(frameset-switch-to-tty-p PARAMETERS)
True when switching to a text-only terminal.
Return non-nil if the parameter alist PARAMETERS describes a frame on a
graphic display, and the frame is being restored on a text-only terminal;
otherwise return nil. Only meaningful when called from a filtering
function in `frameset-filter-alist'.