Emacs custom background color by mode

Question

I use emacs to edit a number of file types, and would like an easy visual queue to tell .c files from .vhd or .py files, for instance. How can I add a custom background col

Answer 1

For posterity, as this thread is 4 years old, it is now possible in Emacs 24.4+ to change faces on a buffer local level. Simply define a face and use (face-remap-add-relative) to swap out whatever face you want with it.

Define a defface:

(defface my-special-face '((t :background "aqua")))

Then add a hook to the mode of your choice:

(add-hook 'python-mode-hook
          (lambda ()
            (face-remap-add-relative 'default 'my-special-face)))