⟩ What are the GWT Panels?
RootPanel is the top level panel.
For layout the page, we could use following layout panels, finally we need to add all those layout panels in RootPanel.
DockLayoutPanel
SplitLayoutPanel
StackLayoutPanel
TabLayoutPanel
Use below panels inside the Layout panels for holding the widgets.
HorizontalPanel
VerticalPanel ( Prefer using FlowPanel )