New Window Features

• The new function window-at tells you which window contains a given horizontal and vertical position on a specified frame. Call it with three arguments, like this:

  (window-at x column frame)
  

  The function returns the window which contains that cursor position in the frame frame. If you omit frame, the selected frame is used.
• The function coordinates-in-window-p takes two arguments and checks whether a particular frame position falls within a particular window.

  (coordinates-in-window-p coordinates window)
  

  The argument coordinates is a cons cell of this form:

  (x . y)
  

  The two coordinates are measured in characters, and count from the top left corner of the screen or frame. The value of the function tells you what part of the window the position is in. The possible values are:

  (relx . rely)

  The coordinates are inside window. The numbers relx and rely are equivalent window-relative coordinates, counting from 0 at the top left corner of the window.

  mode-line

  The coordinates are in the mode line of window.

  vertical-split

  The coordinates are in the vertical line between window and its neighbor to the right.

  nil

  The coordinates are not in any sense within window.

  You need not specify a frame when you call coordinates-in-window-p, because it assumes you mean the frame which window window is on.
• The function minibuffer-window now accepts a frame as argument and returns the minibuffer window used for that frame. If you don't specify a frame, the currently selected frame is used. The minibuffer window may be on the frame in question, but if that frame has no minibuffer of its own, it uses the minibuffer window of some other frame, and minibuffer-window returns that window.
• Use window-live-p to test whether a window is still alive (that is, not deleted).
• Use window-minibuffer-p to determine whether a given window is a minibuffer or not. It no longer works to do this by comparing the window with the result of (minibuffer-window), because there can be more than one minibuffer window at a time (if you have multiple frames).
• If you set the variable pop-up-frames non-nil, then the functions to show something "in another window" actually create a new frame for the new window. Thus, you will tend to have a frame for each window, and you can easily have a frame for each buffer. The value of the variable pop-up-frame-function controls how new frames are made. The value should be a function which takes no arguments and returns a frame. The default value is a function which creates a frame using parameters from pop-up-frame-alist.
• display-buffer is the basic primitive for finding a way to show a buffer on the screen. You can customize its behavior by storing a function in the variable display-buffer-function. If this variable is non-nil, then display-buffer calls it to do the work. Your function should accept two arguments, as follows:

  buffer

  The buffer to be displayed.

  flag

  A flag which, if non-nil, means you should find another window to display buffer in, even if it is already visible in the selected window.

  The function you supply will be used by commands such as switch-to-buffer-other-window and find-file-other-window as well as for your own calls to display-buffer.
• delete-window now gives all of the deleted window's screen space to a single neighboring window. Likewise, enlarge-window takes space from only one neighboring window until that window disappears; only then does it take from another window.
• next-window and previous-window accept another argument, all-frames. These functions now take three optional arguments: window, minibuf and all-frames. window is the window to start from (nil means use the selected window). minibuf says whether to include the minibuffer in the windows to cycle through: t means yes, nil means yes if it is active, and anything else means no. Normally, these functions cycle through all the windows in the selected frame, plus the minibuffer used by the selected frame even if it lies in some other frame. If all-frames is t, then these functions cycle through all the windows in all the frames that currently exist. If all-frames is neither t nor nil, then they limit themselves strictly to the windows in the selected frame, excluding the minibuffer in use if it lies in some other frame.
• The functions get-lru-window and get-largest-window now take an optional argument all-frames. If it is non-nil, the functions consider all windows on all frames. Otherwise, they consider just the windows on the selected frame. Likewise, get-buffer-window takes an optional second argument all-frames.
• The variable other-window-scroll-buffer specifies which buffer scroll-other-window should scroll.
• You can now mark a window as "dedicated" to its buffer. Then Emacs will not try to use that window for any other buffer unless you explicitly request it. Use the new function set-window-dedicated-p to set the dedication flag of a window window to the value flag. If flag is t, this makes the window dedicated. If flag is nil, this makes the window non-dedicated. Use window-dedicated-p to examine the dedication flag of a specified window.
• The new function walk-windows cycles through all visible windows, calling proc once for each window with the window as its sole argument. The optional second argument minibuf says whether to include minibuffer windows. A value of t means count the minibuffer window even if not active. A value of nil means count it only if active. Any other value means not to count the minibuffer even if it is active. If the optional third argument all-frames is t, that means include all windows in all frames. If all-frames is nil, it means to cycle within the selected frame, but include the minibuffer window (if minibuf says so) that that frame uses, even if it is on another frame. If all-frames is neither nil nor t, walk-windows sticks strictly to the selected frame.
• The function window-end is a counterpart to window-start: it returns the buffer position of the end of the display in a given window (or the selected window).
• The function window-configuration-p returns non-nil when given an object that is a window configuration (such as is returned by current-window-configuration).