ADDITIONAL SYSTEM INFORMATION :
Microsoft Windows [Version 10.0.16299.371]

Darwin unit 17.5.0 Darwin Kernel Version 17.5.0: Fri Apr 13 19:32:32 PDT 2018; root:xnu-4570.51.2~1/RELEASE_X86_64 x86_64

JDK under test: C:\\Program Files\\Java\\jdk-10.0.1
java version "10.0.1" 2018-04-17
Java(TM) SE Runtime Environment 18.3 (build 10.0.1+10)
Java HotSpot(TM) 64-Bit Server VM 18.3 (build 10.0.1+10, mixed mode)

A DESCRIPTION OF THE PROBLEM :
The test javax/swing/JComboBox/4523758/bug4523758.java always fails on Windows and MacOS.
The failure was intermittently observed on Linux (one failure per four runs)
The reproducibility on Windows MacOS 100%
on Linux ~25%

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
$ jtreg -testjdk:/cygdrive/c/Program\ Files/Java/jdk-10.0.1 -javaoptions:"-Djava.awt.headless=false" -timeoutFactor:2 test/javax/swing/JComboBox/4523758/bug4523758.java

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
test passes
ACTUAL -
#section:main
----------messages:(5/188)----------
command: main bug4523758
reason: User specified action: run main bug4523758
Mode: othervm
Additional options from @modules: --add-modules java.desktop
elapsed time (seconds): 69.261
----------configuration:(3/43)----------
Boot Layer
  add modules: java.desktop

----------System.out:(1/77)----------
About to screen capture - java.awt.Rectangle[x=0,y=0,width=1707,height=960]
----------System.err:(24/1467)----------
FAIL: ItemEvent not triggered when mouse clicked on combo box drop down
Test failed!
java.lang.RuntimeException: FAIL
at bug4523758.doTest(bug4523758.java:150)
at bug4523758.main(bug4523758.java:159)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:115)
at java.base/java.lang.Thread.run(Thread.java:844)
java.lang.RuntimeException: FAIL
at bug4523758.main(bug4523758.java:162)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:115)
at java.base/java.lang.Thread.run(Thread.java:844)

JavaTest Message: Test threw exception: java.lang.RuntimeException: FAIL
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.RuntimeException: FAIL

---------- BEGIN SOURCE ----------
http://hg.openjdk.java.net/jdk10/jdk10/jdk/file/777356696811/test/javax/swing/JComboBox/4523758/bug4523758.java
---------- END SOURCE ----------

FREQUENCY : always