display-buffer-fallback-action

display-buffer-fallback-action is a variable defined in `window.el'.
Its value is

((display-buffer--maybe-same-window display-buffer-reuse-window display-buffer--maybe-pop-up-frame-or-window display-buffer-in-previous-window display-buffer-use-some-window display-buffer-pop-up-frame))

• This variable may be risky if used as a file-local variable.

Documentation:
Default fallback action for `display-buffer'.
This is the action used by `display-buffer' if no other actions
specified, e.g. by the user options `display-buffer-alist' or
`display-buffer-base-action'. See `display-buffer'.