Re: Side effects in `tooltip-show'

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Po Lu <luangruo@yahoo.com>
>> Cc: emacs-devel@gnu.org
>> Date: Mon, 17 Jan 2022 21:00:46 +0800
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> > How about using 'equal' to compare the strings instead?  What are the
>> > chances that two help-echo strings of 2 different tooltips will
>> > compare equal without the properties, but not with the properties?
>> 
>> That's fine by me as well, but the resulting minor snafu where the
>> tooltip might not be updated if the string contents are identical should
>> be documented somewhere, I think.
>
> In the comments to the code that makes  these comparisons, I think.

Thanks.  Would you mind if I installed this on the release branch?

diff --git a/lisp/tooltip.el b/lisp/tooltip.el
index 1cf16fdb5d..1355eecfcd 100644
--- a/lisp/tooltip.el
+++ b/lisp/tooltip.el
@@ -383,9 +383,12 @@ tooltip-show-help
               ;; Cancel display.  This also cancels a delayed tip, if
               ;; there is one.
               (tooltip-hide))
-             ((equal-including-properties previous-help msg)
-              ;; Same help as before (but possibly the mouse has moved).
-              ;; Keep what we have.
+             ((equal previous-help msg)
+              ;; Same help as before (but possibly the mouse has
+              ;; moved or the text properties have changed).  Keep
+              ;; what we have.  If only text properties have changed,
+              ;; the tooltip won't be updated, but that shouldn't
+              ;; occur often enough to be noticable.
               )
              (t
               ;; A different help.  Remove a previous tooltip, and