Why is JavaFX WebView blinking red and green?

Question

I am just starting with JavaFX and I would like to put a WebView in a window:

public static class HelloJavaFXWeb extends Application { @Override public void start(Stage stage) throws Exception { final Group root = new Group(); Scene scene = new Scene(root, Color.DODGERBLUE); WebView webView = new WebView(); webView.getEngine().load("http://www.google.com"); root.getChildren().add(webView); stage.setTitle("HelloWorld in JavaFX 2.0"); stage.setScene(scene); stage.show(); } } Application.launch(HelloJavaFXWeb.class); 

It looks so simple, but for some reason, the drawing areas are highlighted in red and green when you move the mouse. How to disable blinking colors?

Update: issue related to Groovy / Gradle interaction

Here's an extremely minimal reproducer (put it all in build.gradle and run gradle tasks --no-daemon ):

 buildscript { dependencies { def jvm = org.gradle.internal.jvm.Jvm.current() if (jvm.javaVersion.isJava7()) { classpath files("${jvm.jre.homeDir}/lib/jfxrt.jar") } } } import javafx.application.*; import javafx.scene.*; import javafx.scene.paint.Color; import javafx.scene.web.WebView; import javafx.stage.Stage; class HelloJavaFXWeb extends Application { @Override public void start(Stage stage) throws Exception { final Group root = new Group(); Scene scene = new Scene(root, Color.DODGERBLUE); WebView webView = new WebView(); webView.getEngine().load("http://www.google.com"); root.getChildren().add(webView); stage.setTitle("HelloWorld in JavaFX 2.0"); stage.setScene(scene); stage.show(); } } Application.launch(HelloJavaFXWeb.class); 

I just noticed that it displays some entries after completion
(this was hidden earlier, probably because I used the Gradle daemon that swallowed it):

============ Performance statistics ==============

Amount of time / bills:
com.sun.webpane.perf.WCFontPerfLogger. *: ...
com.sun.webpane.perf.WCGraphicsPerfLogger. *: ...

I am using jdk1.7.0_80_x64/jre/lib/jfxrt.jar for Windows 7 x64 Ultimate.

I tried the following versions of Java that I had on my computer:

 +-----------------+-----------+---------+ | version | flashing | logging | +-----------------+-----------+---------+ | jdk1.7.0_05_x86 | no JavaFX | | jdk1.7.0_80_x64 | yes | yes | | jdk1.7.0_80_x86 | yes | no | | jre1.7.0_80_x86 | yes | no | | jre1.7.0_80_x64 | yes | no | | jre1.8.0_45_x86 | no | no | | jre1.8.0_45_x64 | no | no | +-----------------+-----------+---------+ 

Answer 1

After several hours of immersion in jfxrt.jar , trial and error and using @NwDx, here is a brief description of what is happening.

The Gradle build system works with the root JUL logger and sets the default FINER level to FINER from the source INFO . This activates many of the internal mechanisms inside the JavaFX runtime. Most noticeably:

• Clip area debugging dependent on JUL Logger
• PerfLogger Some JUL Logger Levels
• many other unnecessary protocols, possibly for / dev / null

If you are careless, you can use: LogManager.getLogManager().reset() to fix everything. More careful patients may continue to read.

Click Area Debugging

There is visual debugging code protected by log.isLoggable(Level.FINE) in com.sun.webpane.sg.prism.WCGraphicsPrismContext .

This is a known bug registered here: https://bugs.openjdk.java.net/browse/JDK-8096483 Looking at the fix version: everyone up to 1.8.0u40 is susceptible to this unwanted visual debugging (see the table in the question). In 1.8.0u40 + you can -Dcom.sun.webkit.debugDrawClipShape=true enable this "function".

To be safe, you should turn off logging for this class either by configuring JUL, or:

 String name = com.sun.webpane.sg.prism.WCGraphicsPrismContext.class.getName(); java.util.logging.Logger.getLogger(name).setLevel(java.util.logging.Level.OFF); 

PerfLogger Logging

As mentioned in this question, some diagnostic data is spit out in stdout. PerfLogger checks the FINE level . The source of these messages is as follows:

• com.sun.webpane.perf.WCGraphicsPerfLogger
• com.sun.webpane.perf.WCFontPerfLogger
• com.sun.webpane.platform.Invoker named Locks
• TextBreakIteratorJava in jfxwebkit.dll is called XXXX via LOG_PERF_RECORD
  ... someone literally took an example, why ?: (

The easiest way to disable this:

 java.util.logging.Logger.getLogger('com.sun.webpane.perf').setLevel(Level.OFF) 

because the package name is hard-coded or Logger instances are in that package.

Other

It is probably worth making the log level higher (INFO-OFF) for all com.sun.* And javafx.* to prevent further strangeness or performance degradation.

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