Add window to the right of two horizontally split windows

Question

Following scenario: 1) I start emacs and the initial frame is as follow:

+---------------+
|               |
|               |
|               |
|               |
|               |
+---------------+

1) I split the window horizontally (C-x 2).

+---------------+
|               |
|               |
+---------------+
|               |
|               |
+---------------+

2) now I would like to have one third window, which stretches over the two horizontal ones, resulting in a layout as follow:

+----------+----+
|          |    |
|          |    |
+----------+    +
|          |    |
|          |    |
+----------+----+

How can I achieve this easily without deleting one window (C-x 0), splitting vertically (C-x 3) and then splitting each window horizontally again (C-x 2) ?

My real setup is obviously much more complex, and I resort at the moment to creating a second frame which I would like to avoid.

The same question can be asked for horizontal.

Answer 1

It is possible to split the frame's root window which encompasses both of your windows, thereby allowing you to add a third window at any side. There is no built-in command to do that though, so here's some example code to define commands for this particular task:

(defun my-split-root-window (size direction)
  (split-window (frame-root-window)
                (and size (prefix-numeric-value size))
                direction))

(defun my-split-root-window-below (&optional size)
  (interactive "P")
  (my-split-root-window size 'below))

(defun my-split-root-window-right (&optional size)
  (interactive "P")
  (my-split-root-window size 'right))