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Looking glass is not just helpful for development, but also when asking users to provide relevant information. Having it in-tree makes it easy to reference, and ensures that the documentation is still in a maintained place when plans to retire the wiki go head. The content is based on the [wiki-page] with updated code samples, small sections on added features, and outdated references removed (anyone remember project looking glass?). [wiki-page]: https://wiki.gnome.org/Projects/GnomeShell/LookingGlass Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2932>