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 the Swing application renders as most similar to native applications. On Windows 7, this target is not matched in this place:

A JTree is showing grid lines. Native applications do not show grid lines.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Enable Aero on Windows 7.
Create a swing application showing a JTree.
Enable native PLAF.
Run it.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Must not show grid lines.
ACTUAL -
Shows grid lines.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Application must check whether current OS is Windows 7 and manually switch off grid lines. That makes the application OS aware and such WORA is broken.