(1) Place a semi-transparent Window on top of a solid-colored one.
(2) Ask java.awt.Robot to getPixelColor()

The resulting color will be such as if semi-transparent Window is fully transparent. For instance, for (0,255,0)-colored Window covered by a Window with opacity 0.5f there will be (0,255,0) color.

See attached small test.

Reproducible on Windows XP.
jdk 7 pit build b120 respin test result on windows xp:
the output from the attached test is: java.awt.Color[r=0,g=255,b=0].

so the bug is not fixed in jdk 7 pit build b120.

The test is run on a local computer console.
The exact configuration: Windows XP, Professinaol Version 2002 Service Pack 3. Intel(R) Core(TM) 2 Duo CPU E8400 @3.00GHz.