A live frame is one that has not been deleted. When a frame is deleted, it is removed from its terminal display, although it may continue to exist as a Lisp object until there are no more references to it.
A frame cannot be deleted if its minibuffer is used by other frames. Normally, you cannot delete a frame if all other frames are invisible, but if force is non-
nil, then you are allowed to do so.
nilif the frame frame has not been deleted. The possible non-
nilreturn values are like those of
framep. See Frames.
Some window managers provide a command to delete a window. These work
by sending a special message to the program that operates the window.
When Emacs gets one of these commands, it generates a
delete-frame event, whose normal definition is a command that
calls the function
delete-frame. See Misc Events.