ADDITIONAL SYSTEM INFORMATION :
macOS 10.13.6


A DESCRIPTION OF THE PROBLEM :
My application hang in JavaFX Application Thread.
Here is the output of jstack.
===
"JavaFX Application Thread" #9 daemon prio=5 os_prio=31 tid=0x00007feb03320000 nid=0x307 runnable [0x00007ffeea55b000]
   java.lang.Thread.State: RUNNABLE
at sun.lwawt.macosx.LWCToolkit.doAWTRunLoopImpl(Native Method)
at sun.lwawt.macosx.LWCToolkit.doAWTRunLoop(LWCToolkit.java:825)
at sun.lwawt.macosx.LWCToolkit.invokeAndWait(LWCToolkit.java:642)
at sun.lwawt.macosx.CInputMethod.characterIndexForPoint(CInputMethod.java:757)
- locked <0x0000000792624808> (a sun.lwawt.macosx.CInputMethod)
===

This doesn't occur with 1.8.0_172.