8u40 review request: RT-38183 - ManagedResource warnings when switching screen configurations

[Jim Graham]

webrev: http://cr.openjdk.java.net/~flar/RT-38183/webrev.00/
Jira: https://javafx-jira.kenai.com/browse/RT-38183

Short and long explanations of the fix are in the Jira comments...

                        ...jim