FULL PRODUCT VERSION :
java version "1.8.0-ea"
Java(TM) SE Runtime Environment (build 1.8.0-ea-b119)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b61, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Darwin macbook.local 13.0.0 Darwin Kernel Version 13.0.0: Thu Sep 19 22:22:27 PDT 2013; root:xnu-2422.1.72~6/RELEASE_X86_64 x86_64

A DESCRIPTION OF THE PROBLEM :
With Editable combo box the button is not aligned correctly with the combobox field, at least I don't think so I'm struggling to find an example of editable combo in a native OSX application.
Its worse using size variant small, with non editable combobox its fine.

Same problem on Java 7 and Java 8

This screenshot shows three cases
http://www.jthink.net/jaikoz/images/combos%20not%20aligned.jpg

Language, editable small (JComponent.sizeVariant)
Script, no editable small
Genre, editable normal With Editable combo box the button is not aligned correctly with the combobox field, at least I don't think so I'm struggling to find an example of editable combo in a native OSX application.
Its worse using size variant small, with non editable combobox its fine.


ADDITIONAL REGRESSION INFORMATION:
Same problem with Java 7, not sure about Java 6 because it does look better with Java but I was using the 3rd party Quaqua Look and Feel rather than the Apple one, I dont know what the Apple one would have looked like.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create a panel with an editable combo

JComboBox combo= new JComboBox();
combo.setEditable(true)
//combo.putClientProperty("JComponent.sizeVariant", "small");

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
height of button is in line with height of field
ACTUAL -
height of button is lower than height of field

See http://www.jthink.net/jaikoz/images/combos%20not%20aligned.jpg

REPRODUCIBILITY :
This bug can be reproduced always.