A widget that can hold other widgets. Use panels to construct complex combinations of nested widgets.
Panels can be added to ui.root but not printed to the console with print().
The list of widgets or a single widget to add to the panel. Defaults to an empty array.
The layout to use for this panel. If a string is passed in, it’s taken as a shortcut to the layout constructor with that name. Defaults to 'flow'.
An object of allowed CSS styles with their values to be set for this widget. See style() documentation.