Is there a configuration option in Magit that will force the "git status" window to always appear in a vertical split? I didn't see anything about that in the documentation, and Google was rather useless.
You can control how Magit — and many other modes that open new windows — divide a window by customising the variables
split-width-threshold, and, if you need more control, changing
split-window-preferred-function. These are all documented in the Elisp reference, and see other questions here, e.g. Algorithm on deciding splitting vertically or horizontally
For a reason that I, and others, find puzzling, the default function prefers to split horizontally if possible, so in your case you might want to tweak the variables so that
split-height-threshold is greater than your window's maximum height, and so that a window is never split horizontally.
I asked a similar question recently. You could try this.
(add-to-list 'display-buffer-alist `(,(rx bos "*magit:") (display-buffer-reuse-window display-buffer-below-selected) (reusable-frames . visible) (side . bottom) (window-height . 0.4)))
But I don't use magit frequently and therefore I don't know if this would also open buffers in a vertical split, that you don't want to open that way.
I needed to configure the
In order to not split WINDOW vertically, set (or bind) the variable
split-height-thresholdto nil. Additionally, you can set
split-width-thresholdto zero to make a horizontal split more likely to occur.