This guide intends to provide information on what exactly a composite manager is, and assist you in troubleshooting common issues with the default compositing manager in Ubuntu known as Compiz.
Recent versions of Ubuntu have Compiz Fusion (the merged successor to Compiz and Beryl) enabled by default, along with AIGLX, which is now merged into mainline X.org. XGL is no longer maintained.
When running AIGLX, all windows are rendered to an off-screen buffer. The composite manager is then responsible for drawing the windows to the screen, and has the opportunity to manipulate them, adding in effects such as transparency and wobbliness. There are currently two composite managers available.
- CompositeManager/Compiz - A basic combination of window manager and composite manager from Novell. Now referred to as Compiz Core.
- CompositeManager/CompizFusion - Compiz plus additional features. Includes and requires Compiz Core. If you are familiar with Beryl, this is likely what you want.
Ubuntu currently includes both by default, and takes advantage of both extensively provided your video card can support them.
Known Issues & Troubleshooting
Some applications won't start or are displayed incorrectly
Some applications do not function properly when run along side a composite manager. If after enabling a composite manager you encounter an application that stops working entirely or is displayed incorrectly (often with unwanted transparency), please file a bug. In some cases, you can work around the problem by temporarily disabling alpha visuals for the application, by launching it from the terminal as such:
Replace 'nedit' with the name of the application you are having issues with.
Gnome Panels in Dual-Head Configuration Extend Across Both Monitors
This is a symptom of the way that Gutsy starts Xgl. See https://bugs.launchpad.net/ubuntu/+bug/144758 for a more detailed description and a workaround or fix.