You can't.
The background color is generally frame-specific.
You can set the background color of the default
face to be frame specific using set-face-background
, like so:
(set-face-background 'default "#CCCCCC" (window-frame (frame-selected-window))
Frame customizations are generally controlled through frame parameters. Now, if you look closely at the background-color
for frame parameters, you'll see that the default background color is taken from the default
face - which is why the above elisp has an effect.
Past that, it seems the closes you can come to a buffer background color is by using the minor-mode buffer-face-mode
(added in 23.1) - however that only changes the background for the text of a buffer, and not the entire background.