bug#10275: speedbar highlights first selected item in speedbar-highlight-face

[Chong Yidong]

martin rudalics <rudalics@gmx.at> writes:

> An easy work-around is
>
> (defun speedbar-unhighlight-one-tag-line ()
>   "Unhighlight the currently highlighted line."
>   (when (and speedbar-highlight-one-tag-line
>            (not (eq this-command 'handle-switch-frame)))
>     (speedbar-delete-overlay speedbar-highlight-one-tag-line)
>     (setq speedbar-highlight-one-tag-line nil)
>     (remove-hook 'pre-command-hook 'speedbar-unhighlight-one-tag-line)))

Since no one else has proposed anything better, I've committed this into
trunk for you.