# Package org.zkoss.zul.impl

- Interface Summary
  Interface | Description
  --- | ---
  CaptchaEngine |
  ChartEngine | Chart engine is an engine that do the real chart rendering.
  DataLoader | DataLoader is used with `Grid`, `Listbox` to handle data loading from model to server and then to client side.
  LoadStatus | Denote the status whether a on-demand-loading item is loaded.
  Padding | Control the padding height of a component(Used mainly for component developing).
  TabboxEngine | Tabbox engine is an engine that do the model rendering for `ListModel`

- Class Summary
  Class | Description
  --- | ---
  DateTimeFormatInputElement | A skeletal implementation for date/time type input box.
  FileuploadDlg | Used with `Fileupload` to implement the upload feature.
  FooterElement | A skeletal implementation for a footer.
  FormatInputElement | A skeletal implementation for an input box with format.
  GridDataLoader | Generic `Grid` data loader.
  GroupsListModel<D,​G,​F> | Encapsulates `GroupsModel` as an instance of `ListModel` such that it is easier to handle by `Listbox` and `Group`.
  GroupsListModel.GroupDataInfo | The group information returned by `GroupsListModel.getDataInfo(int)`.
  HeaderElement | A skeletal implementation for a header.
  HeadersElement | A skeletal implementation for headers, the parent of a group of `HeaderElement`.
  InputElement | A skeletal implementation of an input box.
  LabelElement | A XUL element with a label.
  LabelImageElement | A XUL element with a label (`LabelElement.getLabel()`) and an image (`LabelImageElement.getImage()`).
  ListboxDataLoader | Generic `Listbox` data loader.
  ListboxDataLoader.DeferredRedraw |
  MeshElement | The fundamental class for mesh elements such as `Grid`, `Listbox`, and `Tree`.
  MeshElement.InternalPaging |
  MessageboxDlg | Used with `Messagebox` to implement a message box.
  MessageboxDlg.Button | Represents a button on the message box.
  NumberInputElement | A skeletal implementation for number-type input box.
  PageRenderer | The page render for ZUL pages.
  Utils | A collection of utilities.
  XulElement | The fundamental class for XUL elements.
  ZulMessageLoader | ZUL implementation of MessageLoader