GTK+ 3.21.4 introduces various improvements and lots of bugfixes, and, as usual, we’ve managed to get our hands on the internal changelog to tell you what’s new. But first, we would like to inform those not in the known that GTK+ 3.21.4 is a development release towards GTK+ 3.22, which will be distributed as part of the GNOME 3.22 desktop. Among the changes, we can mention support for the new CSS “background-blend-mode,” GdkDrawingContext widget support for the Mozilla Firefox web browser, GtkApplication widget registering support for the Xfce session manager, as well as expanding children for the GtkHeaderBar widget.