form = new Form<PrivateMessage>("form", getModel());
form.add(feedback.setOutputMarkupId(true));
form.add(new UserMultiChoice("to", modelTo).setRequired(true));
form.add(new TextField<String>("subject"));
DefaultWysiwygToolbar toolbar = new DefaultWysiwygToolbar("toolbarContainer");
form.add(toolbar);
form.add(new WysiwygEditor("message", toolbar));
form.add(roomParamsBlock.setOutputMarkupId(true));
final CheckBox bookedRoom = new CheckBox("bookedRoom");
form.add(bookedRoom.setOutputMarkupId(true).add(new AjaxEventBehavior("click") {