GWT Widgets
GWT widgets are user interface elements that are rendered as HTML. Rendering is done either by manipulating the HTML Document Object Model (DOM) through the lower-level DOM API, or simply by injecting the HTML with setInnerHTML(). The layout of the user interface is managed using special panel widgets.
For information about the basic GWT widgets, please refer to the GWT Developer’s Guide at https://developers.google.com/web-toolkit/doc/latest/DevGuideUi.