Run the attached test. You will see a button and an image. Move the mouse over the button. If you see the following exception on the console, bug is reproduced.

Exception in thread "AWT-EventQueue-0" java.lang.IndexOutOfBoundsException: invalid hotSpot
        at sun.awt.CustomCursor.<init>(CustomCursor.java:61)
        at sun.awt.windows.WCustomCursor.<init>(WCustomCursor.java:28)
        at sun.awt.windows.WToolkit.createCustomCursor(WToolkit.java:712)
        at com.sun.javafx.tk.swing.SwingToolkit.convertImageCursorFromFX(SwingToolkit.fx:440)
        at com.sun.javafx.tk.swing.SwingToolkit.convertCursorFromFX(SwingToolkit.fx:391)
        at javafx.scene.Scene$MouseHandler.process(Scene.fx:1522)
        at javafx.scene.Scene$MouseHandler.process(Scene.fx:1361)
        at javafx.scene.Scene.impl_processMouseEvent(Scene.fx:679)
        at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.fx:956)
        at com.sun.javafx.tk.swing.SwingScene$SwingScenePanel.doMouseEvent(SwingScene.java:446)
        at com.sun.javafx.tk.swing.SwingScene$SwingScenePanel.mouseMoved(SwingScene.java:480)
        at java.awt.AWTEventMulticaster.mouseMoved(AWTEventMulticaster.java:312)
        at java.awt.Component.processMouseMotionEvent(Component.java:6308)
        at javax.swing.JComponent.processMouseMotionEvent(JComponent.java:3285)
        at java.awt.Component.processEvent(Component.java:6032)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4251)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2478)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Reproduced on Soma-b30, WinVista.

In the test, I am using an invalid image for the main URL and using a valid placeholder image. The main image is set with a specific width and height. Hotspot values exceed the size of the main as well as placeholder image. So the hotspot is not getting clamped down to valid values in this case.