Bug 65187 [Themes] Cascading*Registry leakage from Colors and Fonts pref page
Small leak on I20040529 For each ColorsAndFontsPreferencePage this is created, the cascading font and color registries are leaked. This is because the superclasses register a runnable with Display#disposeExec
bundles/org.eclipse.jface/src/org/eclipse/jface/resource/ColorRegistry.java
/**
     * This registries <code>Display</code>. All colors will be allocated using 
     * it.
     */
    protected Display display;
    /**
     * Collection of <code>Color</code> that are now stale to be disposed when 
     * it is safe to do so (i.e. on shutdown).
     */
    private List staleColors = new ArrayList();
    /**
     * Table of known colors, keyed by symbolic color name (key type: <code>String</code>,
     * value type: <code>org.eclipse.swt.graphics.Color</code>.
     */
    private Map stringToColor = new HashMap(7);
    /**
     * Table of known color data, keyed by symbolic color name (key type:
     * <code>String</code>, value type: <code>org.eclipse.swt.graphics.RGB</code>).
     */