How to create a custom dialog?

public class DocumentDialog extends ConfiguredDialog {

private String versionName;
/**
      * @param name
      * @param request
      * @param response
      * @param configNode
      */
     public DocumentDialog(String name, HttpServletRequest request, HttpServletResponse response, Content configNode) {
         super(name, request, response, configNode);
         // get a special parameter
         versionName = request.getParameter("mgnlVersion");
     }
 
/**
      * Overriden to force creation if the node does not exist
      */
     protected Save onPreSave() {
         Save save = super.onPreSave();
         save.setCreate(true);
         save.setCreationItemType(ItemType.CONTENTNODE);
         return save;
     }
/*
      * (non-Javadoc)
      * @see info.magnolia.module.admininterface.DialogMVCHandler#onPostSave(info.magnolia.cms.gui.control.Save)
      */
     protected void onPostSave(Save control) {
         super.onPostSave(control);
         Content node = this.getStorageNode();
// .. do something after saving
     }
/**
      * do not reload the tree
      */
     public void renderHtml(String view) throws IOException {
         PrintWriter out = response.getWriter();
// after saving
         if (view == VIEW_CLOSE_WINDOW) {
             // .. do some thing special (perhaps make an alert)
         }
         // show the created dialog
         else {
             super.renderHtml(view);
         }
     }
 }