Hi Leon, Leon Wang wrote: You don't have to do anything special to load your GWT application when the page loads. It should happen by default. You don't need to create a special bootstrapper like XWikiWysiwyg.js for this. You just have to properly import your script file i.e ModuleName.nocache.js . In a XWiki 2.0 page you can easily achieve this with: {{velocity}}$xwiki.jsfx.use("path/to/ModuleName.nocache.js"){{/velocity}} Your onModuleLoad method will be called each time the page loads. Next you have to know where to put your tree in the HTML page. All GWT sample applications append their UIs to the HTML body using RootPanel.get() but that's not good. One way to pass this information to onModuleLoad method is to use a JavaScript configuration object and GWT's Dictionary class. See getConfig(int) method in http://tinyurl.com/ybzdw32 and the Wysiwyg0 JavaScript object in http://tinyurl.com/y9nhaos . The hookId configuration parameter tells me where to put the WYSIWYG editor. Hope this helps, Marius