Plank is a lightweight dock that provides simple functionality: launch applications and alternate between running applications. Here's how to install it in Xubuntu via PPA.
Open a terminal window and run:
sudo add-apt-repository ppa:ricotz/docky -y && sudo apt-get update && sudo apt-get install plank -y
Plank can be accessed via Applications Menu > Accessories > Plank or typing the following command:
Plank doesn't have a graphical configuration interface, you need to edit the text file:
~/.config/plank/dock1/settings. The configuration file has comments that explain how to configure it.
Add launchers to Plank
Right-click on a running application and select "Keep in dock".
Remove launchers from Plank
Drag-and-drop the launcher outside plank.
ReferencesPlank – The Most Lightweight Dock For Ubuntu