How do I make Emacs show blank spaces?

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).

From stackoverflow

• http://www.emacswiki.org/emacs/ShowWhiteSpace

• All the possible settings to do that seem to be summarized here

  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-on)
      ;; ... 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)
    )
  )
  

• WhiteSpace mode is an Emacs minor mode for visualizing all white space characters in the current buffer.

  http://www.emacswiki.org/emacs/WhiteSpace

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

  

  Note: WhiteSpace has now replaced BlankMode

• indent-broken? - never use tabs in your code - disk space is cheap these days.

  Put (setq-default indent-tabs-mode nil) in your .emacs file. Get used to typing C-x h M-x untabify to untabify the entire buffer. To search for tabs type C-s C-i. If you have obscure control characters in your buffers you can see them with M-x hexl-mode.

  Also C-x h M-x indent-region will indent the entire buffer. Some modes like vhdl-mode have a beautify region command.

  warfangle : Different developers on my team have different preferences for tabwidth. Setting everything to spaces screws up the rest of the team. Thanks for playing, though.