https://www.omgubuntu.co.uk/2024/08/gnome-official-status-icons-extension
As part of every GNOME release (spanning GNOME Shell, Mutter, core apps, etc) is an official set of GNOME Shell extensions. This is non-default package is
!gnome
The GNOME Project is a free and open source desktop and computing platform for open platforms like Linux that strives to be an easy and elegant way to use your computer. GNOME software is developed openly and ethically by both individual contributors and corporate partners, and is distributed under the GNU General Public License.
Stock GNOME doesn't have tray icons. If your distribution does show them, they probably preinstalled an extension for you (like Ubuntu does).
Thanks, I'm aware, but that wasn't my question.
This new extension doesn't seem to add support for app indicators.. so what is it for?
Actual legacy tray icons.
AppIndicator more or less allows an application to send an icon and a list of menu items to the desktop environment to be displayed there in some way. Classic tray icons, on the other hand, are actually part of the application that provides them, the system just puts them in a common row for all applications.
While this type of tray icon is more flexible because applications can do anything they want there, AppIndicators are a better/safer solution because ... well, applications just cannot mess around in the system tray as much.
Personally, I thought the classic tray icons were as good as dead (on Linux), but I guess GNOME can always surprise. Not only in removing stuff but also in bringing it back.
The current system tray/app indicator system is kind of a mess.
It adds potential insecurities, and it's just generally untidy and unintuitive - will the icons be monochrome or coloured? When you click it does it open the app? Does it open a context menu? Does instead right clicking open a context menu? Does right clicking open a different context menu? For most people that stuff is minor (they're used to the jank/inconsistency of Windows, after all), but the Gnome team seems to really hate little unintuitive or inconsistency niggles like that.
They've spoken for years about wanting to create a new, standardised, cross-desktop system tray that fixes these issues, but because it requires not only cross-desktop but also third party dev collaboration, progress has been practically non-existent.
I don't know if this specific thing is related (I can't follow the link on my work PC), but if it is, it could be the first step towards the above.
E: nope, it's not that. I'm also puzzled.