See attached testcase (DispTest2.fx). Changing the FloatMap.width/height variables should cause the underlying (Decora level) FloatMap buffer to be resized as well. However, this does not appear to work as it was intended. Currently the implementation of DisplacementMap recreates the Decora-level FloatMap instance but does not reattach the new FM instance to the DM instance, so any setSample() calls go into Never Never Land.

The attached testcase also shows that an exception may be thrown when FloatMap.width/height are set to zero, which needs to be fixed:
Exception in trigger:
java.lang.IllegalArgumentException: Map data must be non-null
at com.sun.scenario.effect.DisplacementMap.setMapData(DisplacementMap.java:91)
at javafx.scene.effect.DisplacementMap$_SBECL.onChange(DisplacementMap.fx:118)
at com.sun.javafx.runtime.location.ObjectVariable.notifyListeners(ObjectVariable.java:142)
at com.sun.javafx.runtime.location.ObjectVariable.replaceValue(ObjectVariable.java:104)
at com.sun.javafx.runtime.location.AbstractBindingExpression.pushValue(AbstractBindingExpression.java:100)
at com.sun.javafx.runtime.location.ObjectVariable$1.compute(ObjectVariable.java:89)
at com.sun.javafx.runtime.location.AbstractVariable.update(AbstractVariable.java:128)
at com.sun.javafx.runtime.location.AbstractVariable.bind(AbstractVariable.java:98)
at com.sun.javafx.runtime.location.AbstractVariable.bind(AbstractVariable.java:88)
at DispTest2.javafx$run$(DispTest2.fx:57)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.sun.javafx.runtime.provider.GUIRuntimeProvider$1.run(GUIRuntimeProvider.java:65)
at com.sun.javafx.tk.swing.SwingToolkit$StartupRoutine.run(SwingToolkit.fx:593)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)