Generalize nemo's custom taskbar jump list to all apps

[edgarogh]

Context

The nemo taskbar icon has a special treatment when it comes to the menu that pops up when you right click it; it has a "Places" accordion list that shows entries that are specific to nemo concepts ("bookmarks", "places").

Other apps, like xed, use Gtk's RecentManager to create a custom jumplist, but it's not very customizable.
I dug through nemo's code to understand how this is done, didn't find anything, then dug through the grouped-window-list's code and found out that it actually has a special case for nemo:

https://github.com/linuxmint/cinnamon/blob/ca8df1fc82b8d068d72bc2b974cc1168952e4122/files/usr/share/cinnamon/applets/grouped-window-list%40cinnamon.org/menus.js#L175-L193

I'm wondering if there's any plans to turn this into an open API that apps can plug into?

Benefits

Quite a few apps could benefit from being able to customize their jumplist further than what Gtk's RecentManager allows (custom icons, custom launch commands, other item group name than "Recents"...), and without being restricted to FreeDesktop's purely static "actions" in desktop files. Examples could include

• Starting a game from a game launchers (e.g. itch, Steam, Lutris, Minecraft Launcher)
• Opening/playing a playlist from a multimedia app (which may be cloud-based, in which case the playlists/artists don't have a local path)
• Opening a discussion with somebody in a messaging app (e.g. Discord, Slack, or some SMS-to-desktop bridge)

Solution?

I don't know exactly how the Mint codebase is structured but I guess this could have its place in XApp? Or does FreeDesktop already have a standard for that, by any chance?

Android's Dynamic App Shortcuts could give quite a few examples of how this is used in practice. Windows also has custom jump lists if I recall correctly from the last time I ever used Windows. This can give API design ideas.