SwingSet2 : Slider leaves tracks in uiScale=2

This issue was reported while lanai testing at JDK-8254003

Steps to reproduce:
1) Launch SwingSet2 with -Dsun.java2d.uiScale=2
2) Select Java Look and Feel
3) Select any theme apart from Ocean theme
4) Go to JSlider tab
5) Move slider from left to right or top to bottom

I have tested on macOS10.15.7 and Windows10 1909 and issue is seen in both the platforms. Looks like generic issue.

Issue is not seen in JDK8u261 but seen in JDK11GA.