bug#60669: Linux Emacs 27.1 custom toolbar icons

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 8 Jan 2023 13:01:26 -0800
> From: David McCracken <davidm@ixont.com>
> 
> The Emacs 27.1 provided (apt-get install) by Ubuntu 22.04 reduces 
> support for custom toolbar icons. It only works with B/W pbm files and 
> only if located in /usr/share/emacs/27.1/etc/images and only if there 
> isn't an xpm file with the same base name. i.e. name.pbm works but not 
> if there is a name.xpm in the directory. If these conditions are not met 
> nothing is displayed.
> 
> This does not seem to be baked into Emacs 27.1 because these 
> restrictions don't exist in Windows Emacs 27.1. They are also not 
> inherent in Linux because they don't exist in Linux Emacs 26.1.
> 
> There are two serious problems with these seemingly unnecessary changes. 
> B/W icons reduce not just the aesthetic quality but also subtle visual 
> clues that help an icon convey its meaning. Accepting only icons in the 
> version-numbered installation directory means that custom icons are 
> wiped out by upgrading Emacs.
> 
> The installer program I provide with my Emacs library stores its (xpm) 
> icons in ~/icons (a directory created by my installer). My library 
> accesses these by e.g.
> (tool-bar-add-item "~/icons/lxa-pin"
> Linux Emacs 27.1 is the only version in which this does not work. To 
> test whether it does not like that the directory is relatively insecure, 
> I tried moving my icons to /usr/local but they were still ignored. In 
> all other versions, adding the xpm extension to the reference causes it 
> to fail but I tested this anyway and it accomplished nothing.

Can you please show a reproducible recipe, starting from "emacs -Q",
that exhibits the problem you are describing?  I don't think I
understand what exactly doesn't work in your case.

Also, please use "M-x report-emacs-bug" to post the details, as that
command collects important details about the Emacs build configuration
that make investigation easier.

Thanks.