Return non-nil when WINDOW is dedicated to its buffer.
More precisely, return the value assigned by the last call of
`set-window-dedicated-p' for WINDOW. Return nil if that function was
never called with WINDOW as its argument, or the value set by that
function was internally reset since its last call. WINDOW must be a
live window and defaults to the selected one.
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' and
`kill-buffer' can delete a dedicated window and the containing frame.
Functions like `set-window-buffer' may change the buffer displayed by a
window, unless that window is "strongly" dedicated to its buffer, that
is the value returned by `window-dedicated-p' is t.
(fn &optional WINDOW)