Dock Applet is a new and very young app that displays on the panel open application window in the form of icons without labels, which ultimately significantly reduces the space on the taskbar when many Windows open and is very useful for small monitors, laptops.
Sorry for the spelling and phonetic errors in the text.
Owner and main writer of MintGuide.org is not a native English speaker.
Under the icon of the running application is displayed by an indicator (with configurable color for dark and light panels) and allows you to move the icons via right-click - left/right.
Here is the applet open Windows by default:
Dock Applet after installation and activation:
Installation into Linux Mint 17/17.1:
sudo add-apt-repository ppa:webupd8team/mate sudo apt-get update sudo apt-get install mate-dock-applet
After the installation is complete Dock Applet, right click on panel - add to panel and in the opened window, select Dock then Add.