FULL PRODUCT VERSION :
owner@owner-VirtualBox:~$ java -version
java version "1.8.0_77"
Java(TM) SE Runtime Environment (build 1.8.0_77-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)
owner@owner-VirtualBox:~$

ADDITIONAL OS VERSION INFORMATION :
owner@owner-VirtualBox:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 14.04 LTS
Release: 14.04
Codename: trusty
owner@owner-VirtualBox:~$


A DESCRIPTION OF THE PROBLEM :
This is a well known look and feel inconsistency which is rooted in the default gtk theme. Several of the properties are wrong related to the size of menu separators and there are no borders at all around popup menu's.

The following stackoverflow discusses the problem, and also provides a solution. The properties that should be changed are listed.
http://stackoverflow.com/questions/1148731/why-do-javas-gtklookandfeel-popups-have-no-border

REGRESSION. Last worked in version 8u77

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) Create a JMenuBar or JMenu as a popup.
2) Set the native GTK look and feel.
3) Show the menu/popup and observe invisible separators and missing borders around menu's.


REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
The current work around is to patch the GTK theme files installed with Java manually. However, they should be fixed in the standard Java release so that users do not need to do this.
http://stackoverflow.com/questions/1148731/why-do-javas-gtklookandfeel-popups-have-no-border

SUPPORT :
YES