Wicket decorator that uses jQuery to block the UI while an Ajax request completes

AjaxBlockUIDecorator.java

import org.apache.wicket.Component;
import org.apache.wicket.ajax.calldecorator.AjaxCallDecorator;

/**
 * Ajax call decorator to block the page while the Ajax callback
 * occurs.
 *
 * For some reason the jQuery plugin used for this decorator continues
 * with a spinning wheel after the response is done until focus leaves
 * the form component. Same thing happens on their web site. Find a better
 * one if needed.
 *
 * @author Jonny Wray
 */
public class AjaxBlockUIDecorator extends AjaxCallDecorator{

    private static final String BLOCK_SCRIPT_MESSAGE = "jQuery.blockUI({ message: '<h3>%s</h3>', overlayCSS: {opacity: .4 } });";
    private static final String BLOCK_SCRIPT_NO_MESSAGE = "jQuery.blockUI({ message: null, overlayCSS: {opacity: .4 } });";
    private static final String UNBLOCK_SCRIPT = "jQuery.unblockUI();";

    private String message = null;

    public AjaxBlockUIDecorator(){}

    public AjaxBlockUIDecorator(String message){
        this.message = message;
    }

    @Override
    public CharSequence decorateScript(Component c, CharSequence script) {
        return message == null ? BLOCK_SCRIPT_NO_MESSAGE + script : String.format(BLOCK_SCRIPT_MESSAGE, message) + script;
    }

    @Override
    public CharSequence decorateOnSuccessScript(Component c, CharSequence script) {
        return UNBLOCK_SCRIPT + script;
    }

    @Override
    public CharSequence decorateOnFailureScript(Component c, CharSequence script) {
        return UNBLOCK_SCRIPT + script;
    }
}