Install xfwm4-themes by entering the following commands in the terminal:
sudo apt update sudo apt install xfwm4-themes
Description:
Theme files for xfwm4
This package contains several theme files for xfwm4, the window manager of the Xfce4 project. If you are unsatisfied with its default theme, then installing this package might be a good idea.
Homepage: http://www.xfce.org/
Version: 4.10.0-2
Section: universe/x11