Install ukui-window-switch by entering the following commands in the terminal:
sudo apt update sudo apt install ukui-window-switch
Description:
Front of the window switch
Front of the window switcher in UKUI desktop environment. Provides the display function(Display window thumbnails and application icons) when the window is switching (press Alt+Tab key).
Homepage: http://www.ukui.org
Version: 1.1.1-0ubuntu1
Section: universe/x11