Everything works OK with XULRunner 1.9.2, but DND fails with XULRunner 1.9.1.2.

STEPS TO REPRODUCE:
1. Import into your workspace the following progect:
https://anonsvn.jboss.org/repos/jbosstools/trunk/jsf/tests/org.jboss.tools.jsf.vpe.jsf.test/resources/jsfTest/
2. Open JBIDE-5042-6229.html in VPE.
3. Select button 'DraggableBn'.
4. Try to drag the button by clicking on the drag icon.

ACTUAL RESULT:
The drag icon disappears (see xulrunner-1.9.1.2.swf).
An XPCOMException is thrown:
org.mozilla.xpcom.XPCOMException: SetupParams failed (0x80004005)
at org.mozilla.xpcom.internal.XPCOMJavaProxy.callXPCOMMethod(Native Method)
at org.mozilla.xpcom.internal.XPCOMJavaProxy.invoke(XPCOMJavaProxy.java:143)
at $Proxy46.invokeDragSession(Unknown Source)
at org.jboss.tools.vpe.dnd.VpeDnD.startDragSession(VpeDnD.java:408)
...
EXPECTED RESULT:
The button is being dragged (see xulrunner-1.9.2.swf).