Fun stuff: GtkConstraintLayout, the equivalent of Apple's AutoLayout and Android's ConstraintLayout, has landed in GTK's master branch, and will be available in the next major release: https://gitlab.gnome.org/GNOME/gtk/merge_requests/973
There's going to be a blog post on the #GTK development blog soon.
Started working on it in late 2016, as a separate library for GTK 3, to be used by Endless for their applications. After writing the layout manager delegate class, I've spent the last 3 months cleaning up the solver and the various moving pieces; with the help of Matthias Clasen, we finally got it merged today, with a lot more features.
More information about constraint layouts: https://blog.gtk.org/2019/07/02/constraint-layouts/
Server run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!