public class Issue1 extends Application {

    public static void main(String[] args) {
        launch(args);
    }
    final ComboBox testedComboBox = new ComboBox();

    @Override
    public void start(Stage stage) throws Exception {
        Pane pane = new Pane();
        pane.setPrefHeight(200);
        pane.setPrefWidth(200);

        pane.getChildren().add(testedComboBox);

        VBox vb = new VBox();

        ToggleButton toggleButton = new ToggleButton();
        
        toggleButton.selectedProperty().bindBidirectional(testedComboBox.editableProperty());

        vb.getChildren().addAll(pane, toggleButton);
        Scene scene = new Scene(vb, 400, 400);
        stage.setScene(scene);
        stage.show();
    }
}

Run Attached code, click toggle button to change to editable state. type "a" to textField of comboBox. Press enter. Catch exception:

java.lang.ArrayIndexOutOfBoundsException: -1
at java.util.ArrayList.elementData(ArrayList.java:371)
at java.util.ArrayList.get(ArrayList.java:384)
at com.sun.javafx.collections.ObservableListWrapper.get(ObservableListWrapper.java:208)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin$2.changed(ComboBoxListViewSkin.java:88)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:367)
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.scene.control.ComboBoxBase.setValue(ComboBoxBase.java:89)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin$4.handle(ComboBoxListViewSkin.java:179)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin$4.handle(ComboBoxListViewSkin.java:173)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$KeyHandler.process(Scene.java:3150)
at javafx.scene.Scene$KeyHandler.access$1800(Scene.java:3080)
at javafx.scene.Scene.impl_processKeyEvent(Scene.java:1500)
at javafx.scene.Scene$ScenePeerListener.keyEvent(Scene.java:1931)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleKeyEvent(GlassViewEventHandler.java:114)
at com.sun.glass.ui.View.handleKeyEvent(View.java:481)
at com.sun.glass.ui.View.notifyKey(View.java:898)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$2$1.run(WinApplication.java:62)
at java.lang.Thread.run(Thread.java:722)


actual for b13 and not actual for b12.