Slider:

- 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

flatlaf-theme-editor/src/main/resources/com/formdev/flatlaf/themeeditor/FlatLafUIKeys.txt

@@ -587,6 +587,8 @@ Slider.focus
 Slider.focusInputMap
 Slider.focusInputMap.RightToLeft
 Slider.focusInsets
+Slider.focusWidth
+Slider.focusedColor
 Slider.font
 Slider.foreground
 Slider.highlight
@@ -601,6 +603,7 @@ Slider.thumbColor
 Slider.thumbWidth
 Slider.tickColor
 Slider.trackColor
+Slider.trackValueColor
 Slider.trackWidth
 Slider.verticalSize
 SliderUI