Bug 805: GraphUI: Add Widget 'marker' (a Group), derived by {MediaUI01 -> MediaPlayer} and new RangeSlider
- A widget specifies specific UI semantics including individual controls.
- Being a {@link Group}, implementations provide shape(s) and its instance can be added to the user's scene.
- Due to the specific nature of widgets,
individual controls/listener may be provided with semantic values.
+++
MediaPlayer exposes a RangeSlider for current position (view and control).
...
Hence GraphUI is ready to implement these so called widgets,
i.e. higher level UI elements based on Group and Shape(s)
and using more convenient CSS like layouting (padding, gap, ..).