Emacs: How can I easily create a new window that spans two existing horizontal windows?

Question

I often have an Emacs frame that is partitioned into two windows like so:

--------------------------------
|                              |
|          Window 1            |
|                              |
|------------------------------|
|                              |
|          Window 2            |
|                              |
--------------------------------

Then I find myself needing a long vertical window that runs the entire height of the frame, like so:

--------------------------------
|         |                    |
| W'dow 3 |      Window 1      |
|         |                    |
|         |--------------------|
|         |                    |
|         |      Window 2      |
|         |                    |
--------------------------------

However, using C-x 3 it's only possible to split either Window 1 or Window 2. The only way to create the long vertical Window 3 is to start again with a single window filling the entire frame, and split it horizontally (then split one of the windows in half again, vertically). This is annoying.

I guess what I'm looking to do is to split the entire frame, rather than just the active window. I've Googled for solutions, but without success. Is it possible to create a new window that runs down the entire length of an Emacs frame, regardless of any windows that already exist inside it?

Answer 1

(split-window 
  (frame-root-window) 
  nil 'left)

Answer 2

This works:

(defun complex-split ()
  (interactive)
  (let (
        (thisBuffer (buffer-name))
        otherBuffer
        )
  (other-window 1)
  (setq otherBuffer (buffer-name))
  (delete-other-windows)
  (split-window-horizontally)
  (other-window 1)
  (split-window-vertically)
  (switch-to-buffer thisBuffer)
  (other-window 1)
  (switch-to-buffer otherBuffer)
  )
)