How can I make my windows transparent by doing Alt+Mouse Scroll?

Pressing and holding Alt + scrolling with the mouse wheel used to give me a transparent window, is there any way I can get that or something similar in Ubuntu 12.04?

Install these packages with the command

sudo apt-get install compizconfig-settings-manager compiz-plugins-extra

This will install the CompizConfig-Settings-Manager and necessary plugins required.

Open the CompizConfig-Settings-Manager by typing ccsm in the dash. In the CCSM's window, under the Accessibility section, enable the Opacity, Brightness and Satuaration by placing a tick mark on the corresponding checkbox.

This should automatically enable the plugin, if it does not, press Alt+F2 and type compiz --replace to restart compiz. A nicer way would be logout and login again.

Now you can increase or decrease the transparency of any window by holding the Alt key and scrolling mouse wheel.

Note: If Unity seems crashed, don't be bothered. Press Ctrl+Alt+Del to bring logout window, and press Enter to logout from your session. Then login again.

For Non-Unity users

Users who are using Lubuntu or Xubuntu, they will miss this feature because those flavor doesn't use Compiz as the window manager. Lubuntu uses OpenBox and Xubuntu uses XFWM window manager. To be able to use this feature, compiz should be used as the window manager.

One way to achieve this is adding a compiz --replace command in startup of the session. (There are neat way of replacing default wm with compiz, but this will do the job)

After enabling compiz, you need to enable some basic plugin using CompizConfig-SettingsManager. These plugins are -

• Window Decoration (For decorating windows)
• Animations
• Maximumize (for maximize)
• Move Window (enable moving)
• Place Window (will place new window in suitable place)
• Resize Window (to be able to resize)
• Application Switcher (Alt-Tab functionality)
• Composite
• OpenGL

These are basics. But you can try others too. I would recommend enabling Scale, Expo, Desktop Wall too.

After enabling these and getting a stable compiz working in your LX/XFCE DE, proceed with the instruction above.