FULL PRODUCT VERSION :
java version "1.8.0_25"
Java(TM) SE Runtime Environment (build 1.8.0_25-b18)
Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
Creating an undercoated and transparent JDialog with a JFrame as its parent will lose transparency upon a JFrame iconify/deiconify sequence.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) Run the test case ( JDialog will display with transparency )
2) Minimize the JFrame
3) Restore the JFrame ( JDialog will be 100% opaque )



EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The expectation is the JDialog will retain opacity setting.
ACTUAL -
All opacity is lost and the JDialog is 100% opaque.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
No error message

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
final JFrame f = new JFrame();
f.setSize(250, 250);

final JDialog d = new JDialog(f, false);
d.setSize(250, 250);
d.setUndecorated(true);
d.setOpacity(.75f);

f.setLocationRelativeTo(null);
d.setLocation(f.getLocation().x + 260, f.getLocation().y);

f.setVisible(true);
d.setVisible(true);
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Various work-a-rounds involve adding a window listener and manipulating visibility and/or opacity and or BG colors but does not always work for all application scenarios. One work-a-round it to simply toggle visibility upon deiconify but that alone does not work for all scenarios.