Bug 230218 [JFace] Test failures in PresentationsTestSuite and RCP Tests
bundles/org.eclipse.jface/src/org/eclipse/jface/resource/ColorRegistry.java
/**
	 * Returns the color descriptor associated with the given symbolic color
	 * name. If this name does not exist within the registry the supplied
	 * default value will be used.
	 * 
	 * @param symbolicName
	 * @param defaultValue
	 * @return the color descriptor associated with the given symbolic color
	 *         name or the default
	 * @since 3.4
	 */
	public ColorDescriptor getColorDescriptor(String symbolicName,
			ColorDescriptor defaultValue) {
		RGB rgb = getRGB(symbolicName);
		if (rgb == null)
			return defaultValue;
		return ColorDescriptor.createFrom(rgb);
	}
    /*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.resource.ResourceRegistry#clearCaches()
	 */
    protected void clearCaches() {
        disposeColors(stringToColor.values().iterator());
        disposeColors(staleColors.iterator());
        stringToColor.clear();
        staleColors.clear();
    }