Showing a TextField with its focused state set to true causes NPE. Here's the testcase:

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import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

public class Main extends Application {
    public void start(Stage stage) {
        TextField text = new TF();

        Pane pane = new Pane();
        pane.getChildren().addAll(text);

        stage.setScene(new Scene(pane));
        stage.show();
        stage.centerOnScreen();
    }

    public static void main(String[] args) {
        Application.launch(Main.class, args);
    }
}

class TF extends TextField {
    public TF() {
        setFocused(true);
    }
}
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The exception:

SEVERE: javafx.scene.control.Control loadSkinClass Failed to load skin 'com.sun.javafx.scene.control.skin.TextFieldSkin' for control TF@10045eb[styleClass=text-input text-field]
java.lang.NullPointerException
        at com.sun.javafx.scene.control.behavior.TextFieldBehavior.setCaretAnimating(TextFieldBehavior.java:110)
        at com.sun.javafx.scene.control.behavior.TextFieldBehavior.<init>(TextFieldBehavior.java:89)
        at com.sun.javafx.scene.control.skin.TextFieldSkin.<init>(TextFieldSkin.java:125)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
        at javafx.scene.control.Control.loadSkinClass(Control.java:857)
        at javafx.scene.control.Control.impl_cssSet(Control.java:935)
        at javafx.scene.Node.impl_cssSet(Node.java:6193)
        at com.sun.javafx.css.StyleHelper.transitionToState(StyleHelper.java:708)
        at javafx.scene.Node.impl_processCSS(Node.java:6067)
        at javafx.scene.Parent.impl_processCSS(Parent.java:951)
        at javafx.scene.control.Control.impl_processCSS(Control.java:962)
        at javafx.scene.Parent.impl_processCSS(Parent.java:958)
        at javafx.scene.Node.processCSS(Node.java:6046)
        at javafx.scene.Scene.doCSSPass(Scene.java:359)
        at javafx.scene.Scene.preferredSize(Scene.java:1132)
        at javafx.scene.Scene.impl_initPeer(Scene.java:568)
        at javafx.stage.Window$13.invalidated(Window.java:683)
        at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:85)
        at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:119)
        at javafx.stage.Window.setShowing(Window.java:741)
        at javafx.stage.Window.show(Window.java:753)
        at javafx.stage.Stage.show(Stage.java:106)
        at textfieldbug.Main.start(Main.java:17)
        at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:298)
        at com.sun.javafx.application.PlatformImpl$4.run(PlatformImpl.java:136)
        at com.sun.javafx.application.PlatformImpl$3.run(PlatformImpl.java:108)
        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:662)


The scenario came from WebView which initializes a control's state right after its creation but before first showing.
So, the NPE is reproducible in WebView.

$ cd apps/internal/Browser
$ ant run -Drun.jvmargs=-DproxyHost=www-proxy.us.oracle.com -Dapplication.args=http://www.wikipedia.org

It will bring up a Browser with wikipedia loaded. Due to the exception WebView fails to show the text field on the page.
This is reproducible with any web page on which there's a text field focused by default. Looks like a stopper for WebView.