5
This Week in Gnome #218 Adaptive Sidebars
(thisweek.gnome.org)
The GNOME Project is a free and open source desktop and computing platform for open platforms like Linux that strives to be an easy and elegant way to use your computer. GNOME software is developed openly and ethically by both individual contributors and corporate partners, and is distributed under the GNU General Public License.
What I did see only at a second glace are those arrows which were added in narrow mode:
As already mentioned. more will probably come in the future