Window with transparent background color.

Components are leaving trails if main window has background color with transparency. Still, window doesn't become transparent even if transparency.
Reproducible: Always.

Reproducible in jdk 8 only (8b118 works normally, starts failing since 8b119 )

Steps to reproduce (as in attached java file):
1. Create window (any kind: Frame, JFrame, or just Window) and place some components on it. Set color with alpha as window's background color.
2. Resize window in any way

Expected:
1. Window with semi-transparent background resized normally

Actual:
1. Window is not transparent at all.
2. Components have trails (see attached screenshot).