Exceptions silently swallowed in DnD listeners, windows only

[adam at adamish.com]

Exceptions silently swallowed in DnD listeners... but only on Windows,
and even in latest 1.8u121 release... This appears to be a bug?? 

I've written up here
http://stackoverflow.com/questions/43488321/javafx-silently-swallowing-exception-raised-in-drag-listeners/43535229#43535229

Short version.... if you have a handler that throws an exception, then
this is silently swallowed, nothing seen in console...

	 destination
.
setOnDragOver
(
new

EventHandler
<
DragEvent
>()

{

public

void
 handle
(
DragEvent
 event
)

{

 event
.
acceptTransferModes
(
TransferMode
.
LINK
);

String
 nullReference 
=

null
;

 nullReference
.
toCharArray
();

// cause an exception

 event
.
consume
();

}

});

My investigation so far.... 

	It appears that native method WinDnDClipboard.push(Object[], int) -
backed by GlassClipboard.cpp [1] swallows the exception silently. A
call back to Throwable.getMessage() can be seen in the debugger but no
exception is printed to the console. 

	The Java 9 version of this file
(http://hg.openjdk.java.net/openjfx/9-dev/rt/file/1a3f128518cd/modules/javafx.graphics/src/main/native-glass/win/GlassClipboard.cpp
[2]) has an additional call to CheckAndClearException(env); as defined
in Utils.cpp, however this is against RT-35400 which appears
unrelated. This has not been backported to Java 8. 
Thanks,

Adam



Links:
------
[1]
http://hg.openjdk.java.net/openjfx/8/master/rt/file/tip/modules/graphics/src/main/native-glass/win/GlassClipboard.cpp
[2]
http://hg.openjdk.java.net/openjfx/9-dev/rt/file/1a3f128518cd/modules/javafx.graphics/src/main/native-glass/win/GlassClipboard.cpp