If you'd like to revert to the look and feel known from FoamTree 2.0.x, you can do so by tweaking a number of options as this example does. Please note that you can still retain some of the 3.0.x improvements, such as zooming or group exposure.
See also the emulation of the Flash-based 1.0.x line of FoamTree.
relaxationInitializerto get polygon layouts known from FoamTree 2.0.x defaults.
groupColorDecoratorto revert to the default color scheme known from FoamTree 2.0.x.