How to: Configuring conditional window transparency in Compiz

Compiz brings a lot of bling to the Linux desktop, but with such an extensive selection of configurable features, it can sometimes be difficult to figure out how to take advantage of specific functionality. Several readers have asked me how to use Compiz to make menus and tooltips transparent, so I figured I'd share this trick with the Open Ended audience.

In order to set up menu transparency, users will need the Compiz Config Settings Manager, which can be acquired on Ubuntu by installing the compizconfig-settings-manager package. Users can launch the utility from the command line or from the GNOME Preferences menu. The settings manager contains a number of tiles that provide access to various plugins and features included in Commpiz. To set menu transparency, select the General Options tile and navigate to the Opacity Settings tab. Expand the Window Opacities section and click the Add button. A small dialog window will open and prompt for window specification and the desired opacity.

In the Opacity Windows text field, you have to input a pipe-separated list of window types to which you want to apply the transparency. I use the following string:

Tooltip | Menu | PopupMenu | DropdownMenu

Then I set the Opacity Window Values field to 90 to indicate that windows of the previously specified types should be 90 percent opaque and 10 percent transparent.

You can also use more elaborate window matching strings that use window class, role, and title. For instance, I like to make all of my Pidgin conversation windows slightly transparent, but not the buddy list. In order to do that, I assign 95 percent opacity to all windows that use the Pidgin class and use the buddy list window title to exclude it from the match list. This is the string I use in the Opacity Windows text box for my Pidgin transparency:

class=Pidgin & !title=Buddy List

You can also use these window matching strings with the Compiz Window Rules plugin to automatically make certain windows adhere to certain behaviors when they are created. For more information about Compiz window matching rules, check out the documentation at the Compiz wiki.