28.15 Dedicated Windows

Functions for displaying a buffer can be told to not use specific windows by marking these windows as dedicated to their buffers. display-buffer (see Choosing Window) never uses a dedicated window for displaying another buffer in it. get-lru-window and get-largest-window (see Cyclic Window Ordering) do not consider dedicated windows as candidates when their dedicated argument is non-nil. The behavior of set-window-buffer (see Buffers and Windows) with respect to dedicated windows is slightly different, see below.

Functions supposed to remove a buffer from a window or a window from a frame can behave specially when a window they operate on is dedicated. We will distinguish three basic cases, namely where (1) the window is not the only window on its frame, (2) the window is the only window on its frame but there are other frames on the same terminal left, and (3) the window is the only window on the only frame on the same terminal.

In particular, delete-windows-on (see Deleting Windows) handles case (2) by deleting the associated frame and case (3) by showing another buffer in that frame’s only window. The function replace-buffer-in-windows (see Buffers and Windows) which is called when a buffer gets killed, deletes the window in case (1) and behaves like delete-windows-on otherwise.

When bury-buffer (see Buffer List) operates on the selected window (which shows the buffer that shall be buried), it handles case (2) by calling frame-auto-hide-function (see Quitting Windows) to deal with the selected frame. The other two cases are handled as with replace-buffer-in-windows.

function window-dedicated-p \&optional window

This function returns non-nil if window is dedicated to its buffer and nil otherwise. More precisely, the return value is the value assigned by the last call of set-window-dedicated-p for window, or nil if that function was never called with window as its argument. The default for window is the selected window.

function set-window-dedicated-p window flag

This function marks window as dedicated to its buffer if flag is non-nil, and non-dedicated otherwise.

As a special case, if flag is t, window becomes strongly dedicated to its buffer. set-window-buffer signals an error when the window it acts upon is strongly dedicated to its buffer and does not already display the buffer it is asked to display. Other functions do not treat t differently from any non-nil value.

You can also tell display-buffer to mark a window it creates as dedicated to its buffer by providing a suitable dedicated action alist entry (see Buffer Display Action Alists).