Bug 48773 [Preferences] Workbench should use ColorRegistry for color management.
Wherever possible, the workbench should use the new Color API for its colors.
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceConverter.java
String name,
		Rectangle value) {
		Rectangle oldValue = getRectangle(store, name);
		if (oldValue == null || !oldValue.equals(value)) {
			store.putValue(name, StringConverter.asString(value));
			store.firePropertyChangeEvent(name, oldValue, value);
		}
	}
	/**
	 * Sets the current value of the preference with the given name
	 * in the given preference store.
	 *
	 * @param store the preference store
	 * @param name the name of the preference
	 * @param value the new current value of the preference
	 */
	public static void setValue(
		IPreferenceStore store,
		String name,
		RGB value) {
		RGB oldValue = getColor(store, name);
		if (oldValue == null || !oldValue.equals(value)) {
			store.putValue(name, StringConverter.asString(value));
			
			JFaceColors.clearColor(name);
			store.firePropertyChangeEvent(name, oldValue, value);
		}
	}
}