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
private Map stringToRGB = new HashMap(7);
    /**
     * Runnable that cleans up the manager on disposal of the display.
     */
    protected Runnable displayRunnable = new Runnable() {
        public void run() {
            clearCaches();
        }
    };
    /**
     * Create a new instance of the receiver that is hooked to the current 
     * display.
     * 
     * @see org.eclipse.swt.widgets.Display#getCurrent()
     */
    public ColorRegistry() {
        this(Display.getCurrent());
    }
    /**
     * Create a new instance of the receiver.
     * 
     * @param display the <code>Display</code> to hook into.
     */
    public ColorRegistry(Display display) {
        Assert.isNotNull(display);
        this.display = display;
        hookDisplayDispose();
    }
    /**
     * Create a new <code>Color</code> on the receivers <code>Display</code>.