The following options provide additional control over the placement of side windows.
If non-nil, the side windows on the left and right of a frame
occupy the frame’s full height. Otherwise, the side windows on the top
and bottom of the frame occupy the frame’s full width.
This option specifies the maximum number of side windows on each side of
a frame. The value is a list of four elements specifying the number of
side window slots on (in this order) the left, top, right and bottom of
each frame. If an element is a number, it means to display at most that
many windows on the corresponding side. If an element is nil, it
means there’s no bound on the number of slots on that side.
If any of the specified values is zero, no window can be created on the
corresponding side. display-buffer-in-side-window will not
signal an error in that case, but will return nil. If a specified
value just forbids the creation of an additional side window, the most
suitable window on that side is reused and may have its
window-slot parameter changed accordingly.
This option specifies whether top/bottom side windows should appear in
reverse order. When this is nil, side windows on the top and
bottom of a frame are always drawn from left to right with increasing
slot values. When this is t, the drawing order is reversed and
side windows on the top and bottom of a frame are drawn from right to
left with increasing slot values.
When this is bidi, the drawing order is reversed if and only if
the value of bidi-paragraph-direction (see Bidirectional Display) is right-to-left in the buffer displayed in the window
most recently selected within the main window area of this frame.
Sometimes that window may be hard to find, so heuristics are used to
avoid that the drawing order changes inadvertently when another window
gets selected.
The layout of side windows on the left or right of a frame is not affected by the value of this variable.
When a frame has side windows, the following function returns the main window of that frame.
This function returns the main window of the specified frame. The optional argument frame must be a live frame and defaults to the selected one.
If frame has no side windows, it returns frame’s root
window. Otherwise, it returns either an internal non-side window such
that all other non-side windows on frame descend from it, or the
single live non-side window of frame. Note that the main window
of a frame cannot be deleted via delete-window.
The following command is handy to toggle the appearance of all side windows on a specified frame.
This command toggles side windows on the specified frame. The optional argument frame must be a live frame and defaults to the selected one.
If frame has at least one side window, this command saves the
state of frame’s root window in the frame’s
window-state frame parameter and deletes all side windows on
frame afterwards.
If frame has no side windows, but does have a window-state
parameter, this command uses that parameter’s value to restore the side
windows on frame leaving frame’s main window alone.
An error is signaled if frame has no side windows and no saved state is found for it.