## Tool tips on text in Emacs

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Here we look at a way to get tool tips on text in Emacs. This would be helpful for giving hints, or definitions, or reminders about something. Tool tips are created by setting the help-echo text property for the string of interest. We will write a function that adds the tool tip to every instance of a string in the current buffer. We will also change the color of the string slightly to give the reader a hint there might be something there.

Here is the code. We use save-excursion so that the cursor stays where it starts. Then we search for the string we want a tool tip on, and set the appropriate properties.

What is a foobar?

; add a tooltip to every instance of foobar
(save-excursion  ;return cursor to current-point
(goto-char 1)
(while (search-forward "foobar" (point-max) t)
(set-text-properties  (match-beginning 0) (match-end 0)
(help-echo "You know... a bar for foos!"
font-lock-face (:foreground "dark slate gray"))
)))
`

After you run the function above, the next sentence should have a grayed word in it, and when you hold your mouse over the grayed word a tool tip should appear.

There is a foobar in the woods.

You can see the effect here:

This could be an interesting way to increase the depth and richness of text. To use it you would have to define a function that runs when a file is opened, or call the function after opening a file.