Operator script (click here to toggle)

In the top test, the green rectangle should appear on top of the blue rectangle.

In the second test, the blue rectangle should not show through in the region where the green and blue overlap.

In the third test, the blue rectangle should show through in the overlap region.

Lastly, the result should be similar to the previous test only fainter (because the opacity) is resulting in less contribution.

The rendered picture should match the reference image exactly, except for possible variations in the labelling text (per CSS2 rules).