1) drop 2 buttons into the scene
2) change the "Text Fill" of Button1 to RED
3) select both Botton1 and Button2 (multi-selection)
4) change the "Text Fill" in the inspector, you will get the following exception.

Glass detected outstanding Java exception at -[GlassViewDelegate sendJavaMouseEvent:]:src/com/sun/mat/ui/GlassViewDelegate.m:540
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at com.oracle.javafx.authoring.presenters.valueeditors.SlotValueEditor.setModelValue(SlotValueEditor.java:355)
at com.oracle.javafx.authoring.presenters.valueeditors.PaintCustomizer.updateModel(PaintCustomizer.java:75)
at com.oracle.javafx.authoring.presenters.valueeditors.PaintCustomizer.access$000(PaintCustomizer.java:26)
at com.oracle.javafx.authoring.presenters.valueeditors.PaintCustomizer$2.changed(PaintCustomizer.java:60)
at com.oracle.javafx.authoring.presenters.valueeditors.PaintCustomizer$2.changed(PaintCustomizer.java:56)
at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:196)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:100)
at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:123)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:130)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:163)
at javafx.beans.property.ObjectProperty.setValue(ObjectProperty.java:84)
at com.oracle.javafx.authoring.choosers.PaintChooserPane2$2.changed(PaintChooserPane2.java:81)
at com.oracle.javafx.authoring.choosers.PaintChooserPane2$2.changed(PaintChooserPane2.java:77)
at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:196)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:100)
at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:123)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:130)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:163)
at javafx.beans.property.ObjectProperty.setValue(ObjectProperty.java:84)
at com.oracle.javafx.authoring.choosers.PaintChooserPane.setPaint(PaintChooserPane.java:220)
at com.oracle.javafx.authoring.choosers.PaintChooserPane$1.setColor(PaintChooserPane.java:73)
at com.oracle.javafx.authoring.choosers.SBColorPicker$ColorSquare$1.handle(SBColorPicker.java:90)
at com.oracle.javafx.authoring.choosers.SBColorPicker$ColorSquare$1.handle(SBColorPicker.java:84)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$ClickGenerator.postProcess(Scene.java:3078)
at javafx.scene.Scene$ClickGenerator.access$8600(Scene.java:3016)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3298)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3129)
at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3084)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1524)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2226)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:227)
at com.sun.glass.ui.View.handleMouseEvent(View.java:528)
at com.sun.glass.ui.View.notifyMouse(View.java:922)