30.4 Frame Parameters

A frame has many parameters that control its appearance and behavior. Just what parameters a frame has depends on what display mechanism it uses.

Frame parameters exist mostly for the sake of graphical displays. Most frame parameters have no effect when applied to a frame on a text terminal; only the height, width, name, title, menu-bar-lines, buffer-list and buffer-predicate parameters do something special. If the terminal supports colors, the parameters foreground-color, background-color, background-mode and display-type are also meaningful. If the terminal supports frame transparency, the parameter alpha is also meaningful.

By default, frame parameters are saved and restored by the desktop library functions (see Desktop Save Mode) when the variable desktop-restore-frames is non-nil. It’s the responsibility of applications that their parameters are included in frameset-persistent-filter-alist to avoid that they get meaningless or even harmful values in restored sessions.