In release 0.8.1 we made a change to the visual editor's rendering engine preferences (to see what I'm talking about navigate to Window > Preferences > EGL > Rich UI > Appearance, section at the bottom). There's no longer a 'default' option, as that was leading to confusion as it differs from system to system. The new preferences are more explicit about which engine to use, and we only display options that are supported on your operating system and architecture. Linux users will also see a 'User configured' option which will use the default engine as configured per the SWT FAQ, since many such systems aren't set up to "work out of the box".
For more information on what's supported, see the "Rendering Engines" section at http://wiki.eclipse.org/EDT:Supported_Platforms.
Is this more complicated than it should be? YES. But we're limited by what SWT supports and the manual configurations, if any, SWT requires.
Also worth noting is a new button in the visual editor's toolbar:
Clicking on this question mark will display the user agent of the rendering engine being used by the visual editor - especially useful when using the 'User Configured' option. It would also be useful to include the user agent information when opening bug reports related to Rich UI runtime errors.