Mark WINDOW as dedicated according to FLAG.
WINDOW must be a live window and defaults to the selected one. FLAG
non-nil means mark WINDOW as dedicated to its buffer. FLAG nil means
mark WINDOW as non-dedicated. Return FLAG.
When a window is dedicated to its buffer, `display-buffer' will refrain
from displaying another buffer in it. `get-lru-window' and
`get-largest-window' treat dedicated windows specially.
`delete-windows-on', `replace-buffer-in-windows', `quit-window',
`quit-restore-window' and `kill-buffer' can delete a dedicated window
and the containing frame.
As a special case, if FLAG is t, mark WINDOW as "strongly" dedicated to
its buffer. Functions like `set-window-buffer' may change the buffer
displayed by a window, unless that window is strongly dedicated to its
buffer. If and when `set-window-buffer' displays another buffer in a
window, it also makes sure that the window is no more dedicated.
(fn WINDOW FLAG)