- changed default color to bluish
- made track thinner (2px, was 3px)
- made thumb larger (12px, was 11px)
- added thumb outline focus indicator (4px wide)
- slider component height increased from 11px to 20px
- support painting thumb border
- support different colors for thumb background and colored track
- updated with latest changes from FlatSliderUI
- use static FlatSliderUI methods for thumb painting
- hover/pressed feedback on single thumb
- hover/pressed feedback on middle track and both thumbs
- added JSlider components to FlatRangeSliderTest for easier testing/comparing
- use rounded rectangles for buttons in tab area
- "pressed" background for buttons in tab area
- fill background of buttons in tab area
- use derived colors for hover and pressed
- fixed missing arrow in "more tabs" button at larger scaling
- made tabs separator color lighter in dark themes so that it is easier to recognize the tabbed pane
- added top and bottom tab insets to avoid that large tab icons are painted over active tab underline
