How do I make Emacs show blank spaces?

Question

How can I make Emacs show blank spaces (like a space, a tab, a line-jump, etc). Many other editors like Kate and Eclipse have this feature and I find it very useful to see when code is indent-broken because of mix of spaces and tabs (particularly Python).

Answer 1

WhiteSpace mode is an Emacs minor mode for visualizing all white space characters in the current buffer. It can be activated with M-x whitespace-mode.

Here is a screenshot of WhiteSpace in action taken directly from the Emacs wiki,

Note: WhiteSpaceMode has now replaced BlankMode

Answer 2

All the possible settings to do that seem to be summarized here (blank-mode) and here and here (ShowWhiteSpace)

also:

(if (>= emacs-major-version 22)   (progn     ;; Mode to use with Emacs 22     ;; http://emacswiki.org/cgi-bin/wiki/BlankMode     (require 'blank-mode)     ;; Mode not active by default: let's activate it     (global-blank-mode t)     ;; ... activate it when text mode where color syntax is not active by default     (add-hook 'text-mode-hook 'blank-mode-on)     ;; All invisible chars are shown, except newline char.     (setq blank-chars '(tabs spaces trailing lines space-before-tab))     ;; Show only for one color, no mark inserted     (setq blank-style '(color))     ;; Use for normal space (not shown)     (set-face-background 'blank-space-face nil)     (set-face-foreground 'blank-space-face "black")     ;; used for non breakable space     (set-face-background 'blank-hspace-face "PaleGreen")     (set-face-foreground 'blank-hspace-face "black")     ;; Used for spaces left of a tab     (set-face-background 'blank-space-before-tab-face "orange")     (set-face-foreground 'blank-space-before-tab-face "black")     ;; Used for tab     (set-face-background 'blank-tab-face "lemonchiffon")     (set-face-foreground 'blank-tab-face "black")     ;; used for extra space at the end of a line     (set-face-background 'blank-trailing-face "gold")     (set-face-foreground 'blank-trailing-face "black")     ;; Used for line too long     (set-face-background 'blank-line-face "snow2")     (set-face-foreground 'blank-line-face "black")   )   (progn     ;; For older Emacs prior to version 22.     ;; http://www.emacswiki.org/cgi-bin/wiki/show-wspace.el     (require 'show-wspace)     (add-hook 'font-lock-mode-hook 'show-ws-highlight-tabs)     (add-hook 'font-lock-mode-hook 'show-ws-highlight-hard-spaces)     (add-hook 'font-lock-mode-hook 'show-ws-highlight-trailing-whitespace)   ) )