On the default Unity desktop, we can click on the left panel icons to launch or focus applications. Then do you want to minimize an application window by clicking on its shortcut icon on left launcher?
Well, we can easily enable this feature in Ubuntu 15.04 via below steps:
1. Open Ubuntu Software Center, search for and install Unity Tweak Tool, a graphical configuration tool for the default Unity desktop:
2. After installing this tool, search for and launch it from the Unity Dash.
3. When the tool opens, click the first icon Launcher to go into its configuration page, and check the box where it says “Minimize single window applications on click”.
That’s it. Enjoy!