# Package org.zkoss.zk.ui

- Interface Summary
  Interface | Description
  --- | ---
  Component | An UI component.
  Desktop | Represents a desktop.
  Execution | An execution of a client request (e.g., ServletRequest).
  IdSpace | Implemented by a component (`Component`) and a page (`Page`) to denote that all its descendant and itself forms an independent ID space.
  Page | A page.
  Richlet | Defines methods that all richlets must implement.
  RichletConfig | A richlet configuration object used by a richlet container to pass information to a richlet during initialization.
  Session | A user session.
  ShadowElement | A shadow element can allow to have a set of shadow elements to work with a component tree and it can also support with ZK MVVM to dynamically change the content of a shadow element.
  ShadowElementCtrl | An addition interface to `ShadowElement`
  WebApp | Represents a Web application.

- Class Summary
  Class | Description
  --- | ---
  AbstractComponent | A skeletal implementation of `Component`.
  AbstractComponent.ForwardInfo |
  AbstractComponent.TargetInfo |
  AbstractPage | A skeletal implementation of `Page`.
  Components | Utilities to access `Component`.
  Executions | Utilities to access `Execution`.
  GenericRichlet | Defines a generic richlet.
  HtmlBasedComponent | A skeletal implementation for HTML based components.
  HtmlMacroComponent | The implementation of a macro component for HTML-based clients.
  HtmlNativeComponent | A component used to represent XML elements that are associated with the native namespace (http://www.zkoss.org/2005/zk/native).
  HtmlNativeComponent.HtmlHelper | The HTML helper.
  HtmlShadowElement | A skeleton of shadow element that represents as a shadow tree.
  Path | A representation of a component path.
  Sessions | Utilities to access `Session`.
  Templates | Utils for looking up template.
  UiException.Aide | Utilities to wrap `UiException`.
  WebApps | Utilities related to the Web application.

- Enum Summary
  Enum | Description
  --- | ---
  HtmlShadowElement.Direction | A help class for an insertion direction.

- Exception Summary
  Exception | Description
  --- | ---
  ActivationTimeoutException | Indicates the activation of an execution is taking too long.
  ArithmeticWrongValueException | For ArithmeticException wrong value wrapper.
  ComponentNotFoundException | Denotes a component cannot be found.
  DesktopUnavailableException | Denotes the desktop being accessed is no longer available.
  OperationException | The operation exception is a special UI exception that happens 'reasonably' -- usually caused by user rather than by programming error.
  SuspendNotAllowedException | Denotes the current event processing thread cannot be suspended because there are too many suspended threads.
  UiException | Represents a UI-relevant runtime exception.
  WrongValueException | Denotes the value passed to a setter (a.k.a., mutator) of a component is wrong.
  WrongValuesException | Denotes an exception that is an aggregation of multiple `WrongValueException`.