FULL PRODUCT VERSION :
java version "1.6.0_18"
Java(TM) SE Runtime Environment (build 1.6.0_18-b07)
Java HotSpot(TM) Client VM (build 16.0-b13, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7600]

EXTRA RELEVANT SYSTEM CONFIGURATION :
Aero enabled

A DESCRIPTION OF THE PROBLEM :
When using the native PLAF, it is expected that a Swing applications renders similar to a native one. This is not true in this situation:

JTree and JTable both are rendering their selection bars as "flat", dark blue backgrounds. Native applications instead render their selections bars as "convex", light blue gradients.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Enable Aero on Windows 7.
Create a JTable or JTree.
Select one line in that.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The selected line should render as a light "convex" gradient.
ACTUAL -
The selected line renders as a dark blue "flat" background.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Application must check whether it is running on Windows 7. This makes the application OS aware and such breaks the WORA principle.