bug#52142: 28.0.60; `posn-object-width-height' does not reflect actual dimensions of object when confronted by display string

[Eli Zaretskii]

tags 52142 notabug
thanks

> Date: Sat, 27 Nov 2021 20:00:17 +0800
> From:  Po Lu via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> In Emacs -Q, run M-x report-emacs-bug RET, move point to the message
> intended for novices (This bug report will be sent to the Bug-GNU-Emacs
> mailing list ...), and then evaluate (posn-at-point) there.
> 
> The posn-object of the position list will be the display string
> containing the entire message, but the posn-object-width-height will
> contain the dimensions of the first character of the message, in this
> case "T".

That's a feature.  Maybe it isn't documented clearly enough, but
basically as long as there's a character displayed at that position,
WIDTH and HEIGHT give the dimensions of that character's glyph on
display.

Remember: this stuff was originally designed for mouse clicks, where
it's important to know what did you click on.