testing the beta version of the user environment . Release in October or November. The most notable change in the new branch is the translation of the interface to the GtkHeaderBar widget and the use of client-side window decoration (CSD), which allowed for the placement of menus, buttons, and other interface elements in the window header.
Other changes include the cessation of optional GTK2 support, the implementation of symbolic icon variants, of interface elements based on GtkTreeViews, features of the Thunar file manager.
Source: opennet.ru
