ScrolledWindow.addWithViewport

Used to add children without native scrolling capabilities. This is simply a convenience function; it is equivalent to adding the unscrollable child to a viewport, then adding the viewport to the scrolled window. If a child has native scrolling, use [gtk.container.Container.add] instead of this function.

The viewport scrolls the child by moving its #GdkWindow, and takes the size of the child to be the size of its toplevel #GdkWindow. This will be very wrong for most widgets that support native scrolling; for example, if you add a widget such as #GtkTreeView with a viewport, the whole widget will scroll, including the column headings. Thus, widgets with native scrolling support should not be used with the #GtkViewport proxy.

A widget supports scrolling natively if it implements the #GtkScrollable interface.