rangeThumbShape property Null safety
The shape that will be used for the RangeSlider's thumbs.
By default the same shape is used for both thumbs, but strokes the top thumb when it overlaps the bottom thumb. The top thumb is always the last selected thumb.
The default value is RoundRangeSliderThumbShape.
- RoundSliderThumbShape, which is the default thumb shape for the Slider.
final RangeSliderThumbShape? rangeThumbShape;