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For the most part I prefer to disable Emacs' fringe with fringe-mode no-fringes. But I like to have the left fringe active when debugging elisp code (for the little fringe arrow pointing to the active line).

I found edebug-setup-hook for setting fringe-mode to left-only when entering edebug, but I'm fairly certain that's not what that hook is for. (Basing that on the fact that Emacs resets edebug-setup-hook to nil all the time.)

Is there a way to set fringe-mode back to no-fringes upon exiting the debugger? Is there a better way to set it to left-only upon entering?

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I think this does what you are asking for:

(add-hook 'edebug-mode-hook
          (lambda ()
             (set (make-local-variable 'fringe-mode)
                  (if edebug-mode '(nil . 0) 0)))))
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Which version of Emacs are you using? I've got 24.3.1, and mine doesn't have edebug-mode or an edebug-mode-hook. – purple_arrows Sep 17 '13 at 15:05
Emacs 24.3 does have edebug-mode, but you have to first load library edebug.el to then see it using C-h f. Each mode is defined to use a mode hook variable, if one is referenced (e.g., by add-hook). IOW, the variable does not need to preexist --- this is true of modes in general. – Drew Sep 17 '13 at 17:16
Coming back to this question more than a year too late, my apologies. The code as given did not work, I think because edebug is implemented as a recursive edit, not a true minor mode. Mind if I move to the new emacs.SE? – purple_arrows Oct 5 '14 at 19:00
I certainly don't mind. Hope you find what you are looking for. Wrt the code above, you might want to say what "did not work" amounts to. – Drew Oct 6 '14 at 3:36

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