digraph Widgets
{
    Widget [color=lightgrey];
    Bar [color=lightgrey];
    ScrollBar [color=lightgrey];

    Widget -> Frame;
              Frame -> Window;
              Frame -> TabFrame;
    Widget -> Viewport;
    Widget -> MenuItem;
              MenuItem -> MenuSeparator;
    Widget -> Bar;
              Bar -> TabBar;
              Bar -> TitleBar;
              Bar -> ScrollBar;
                     ScrollBar -> HScrollBar;
                     ScrollBar -> VScrollBar;
              Bar -> StatusBar;
              Bar -> ToolBar;
              Bar -> MenuBar;
    Widget -> TextBox;
              TextBox -> TextArea;
                         TextArea -> Label;
                                     Label -> FadingLabel;
    Widget -> Button;
              Button -> TitleButton;
              Button -> ToggleButton;
              Button -> RadioButton;
              Button -> TabButton;
}
