The feature was last supported in Ubuntu 12.04 Precise LTS. Now it comes back in Ubuntu 14.04 Trusty LTS and here is how to enable it.
Once screencast is enough:
To get started:
- Search for and install compizconfig settings manager via Ubuntu Software Center. Or install it via terminal (Ctrl+Alt+T) command:
sudo apt-get install compizconfig-settings-manager
- Open CCSM from Unity Dash.
- Click “Ubuntu Unity Plugin” and then navigate to the Launcher tab.
- Enable “Minimize Single Window Applications (Unsupported)” by check the box after that line
That’s it. Enjoy!