What are layout panels? List Basic Panels available in GWT?

Layout panels are the most general layout mechanism, upon which other layouts are built. Layout panel contains other widgets which control the way widgets to be shown on User Interface. The panel widgets follow the properties of panel class which means inherits properties from panel class. These panel class takes the properties from widget class which in turns takes the properties from UIObject class.

List of Basic panels available in GWT:

• Root panel: it is the topmost panel and all other widgets are attached are attached to it. Use RootPanel.get(String id) to obtain a panel for any other element on the page.
• Flow panel: It is the simplest panel which creates a single
  element and attaches children to it without any modification.
• HTML panel: This panel offers a simple way to define HTML structures, most commonly used in UiBinder templates.
• Form panel: it is used to reproduce the behavior of an HTML form.
• Scroll panel: it is used to create a scrollable area within another panel.
• Popup panel and DialogBox panel: To create simple pops and dialogs, these panels are used.
• Grid and Flex table: these are used to create HTML table elements.