This is the best way to get rid of the gutter in tools like speedbar and
ediff
(defun turn-off-top-gutter ()
(set-specifier top-gutter-visible-p nil (current-buffer)))
(add-hook 'ediff-before-setup-control-frame-hook 'turn-off-top-gutter)
(add-hook 'speedbar-mode-hook 'turn-off-top-gutter)