Try to fix disambiguaties by:
- Remove optional constraints, instead set width constraint to 0
  to hide fullscreen button
- Decrease content hugging priority to 200 for slider (this should
  always expand)
- Fix some width constraints in detached window: Each button group
  does not define a width, but the (sometimes) intrinsic or
  explicit size define the with of the entire group

General fixes:
- Order slider in list according to appearance