In addition to the recent merge to Mutter for [1]improving fullscreen apps with direct scanout enhancements for GNOME 49, another early addition also landed today in Mutter: support for Wayland's toplevel tag protocol.

The Toplevel Tag protocol was introduced earlier this month in [2]Wayland Protocols 1.43 via xdg_toplevel_tag_v1 .This allows for Wayland clients to tag top-levels in a script-friendly manner. This protocol discussion goes back two years and for helping compositors identify windows with persistent identification capabilities.

The toplevel tag protocol can be used for helping compositors restore window positioning/sizes after a restart, honoring "always on top" window behavior, and for allowing custom rules for the compositor that target specific windows based on their tags.

[3]This Mutter merge request has been open the past seven months and finally merged today for landing toplevel tag support.

"It allows to identify unique toplevels (windows) in order to set their initial size and position

...

Useful for identifying per app windows, which would help with configurability and scriptability.

A backward compatible path for X11 is implemented using a new X11 Atom."

So another Wayland addition to look forward to with GNOME 49 in September.



[1] https://www.phoronix.com/news/GNOME-49-Better-Direct-Scanout

[2] https://www.phoronix.com/news/Wayland-Protocols-1.43

[3] https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4043