A customer recently upgraded to JDK 8u60 and was experiencing deadlocks in their swing client application on Mac.
To reproduce start the attached main class, drop a file from Mac finder onto the window. This will open a modal dialog. With java 8u60 or 8u66-b02 it is not possible to close the dialog when running under OS X. With 8u51/OS-X or 8u60/Windows the bug does not appear. The GUI and the source should be self-explanatory.