. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282 25.9. Validators must not change any data or models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . visitChildren. Starting from Wicket 8 the same task can be accomplished using the stream object returned by methods stream (which contains only the direct children) and streamChildren (which contains all will have the following set of panels: • HeaderPanel • FooterPanel • MenuPanel Content area will change from page to page, so we don’t need a reusable panel for it. 5.3.2. Template page Now we can build

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 25.9. Validators must not change any data or models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . visitChildren. Starting from Wicket 8 the same task can be accomplished using the stream object returned by methods stream (which contains only the direct children) and streamChildren (which contains all will have the following set of panels: • HeaderPanel • FooterPanel • MenuPanel Content area will change from page to page, so we don’t need a reusable panel for it. 5.3.2. Template page Now we can build

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 25.9. Validators must not change any data or models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 visitChildren. Starting from Wicket 8 the same task can be accomplished using the stream object returned by methods stream (which contains only the direct children) and streamChildren (which contains all will have the following set of panels: • HeaderPanel • FooterPanel • MenuPanel Content area will change from page to page, so we don’t need a reusable panel for it. 5.3.2. Template page Now we can build

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 25.9. Validators must not change any data or models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 have the following set of panels: • HeaderPanel 21 • FooterPanel • MenuPanel Content area will change from page to page, so we don’t need a reusable panel for it. 5.3.2. Template page Now we can build recommended not to directly override these method, but rather to use onConfigure to change component states. On the contrary method onBeforeRender (see the next paragraph)

Code AjaxFormComponentUpdatingBehavior ajaxBehavior = new AjaxFormComponentUpdatingBehavior("change"){ @Override protected void onUpdate(AjaxRequestTarget target) { //... }