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/FontRegistry.java
return null;
        } else {
            
            put(symbolicName, validData, false);
            Font newFont = new Font(display, validData);
            return new FontRecord(newFont, validData);
        }
    }
    /**
     * Calculates the default font and returns the result
     */
    Font calculateDefaultFont() {
        Display current = Display.getCurrent();
        if (current == null) {
            Shell shell = new Shell();
            Font font = new Font(null, shell.getFont().getFontData());
            shell.dispose();
            return font;
        } else
            return new Font(current, current.getSystemFont().getFontData());
    }
    /**
     * Returns the default font data.  Creates it if necessary.
     * @return Font
     */
    public Font defaultFont() {
        return defaultFontRecord().getBaseFont();
    }
    /**
     * Returns the default font record.