A new milestone was released recently, GTK+ 3.91.0, which adds a quite a bunch of improvements and bug fixes, but also some new APIs and compatibility with other supported operating systems besides those based on the Linux kernel. For example, GTK+ 3.91.0 implements initial support for Apple’s macOS platform, which will make it possible to run apps written in GTK+ 4 on OS X. Another highly anticipated feature is support for building GTK+ with the Meson build system, which is being adopted by more and more open source projects these days. Moreover, GTK+ 3.91.0 introduces a new API (Application Programming Interface) called gtk_widget_insert_before/after, and removes the expand and fill child properties from GtkBox, as well as the angle property from GtkLabel.