import com.sun.awt.AWTUtilities;

import sun.awt.SunToolkit;

import javax.swing.*;

import java.awt.*;

import java.awt.image.BufferedImage;

public class bug6683775 {

public static void main(String[] args) throws Exception {

GraphicsConfiguration gc = getGC();

if (!AWTUtilities.isTranslucencySupported(

AWTUtilities.Translucency.PERPIXEL_TRANSLUCENT)

|| gc == null) {

return;

}

SunToolkit toolkit = (SunToolkit) Toolkit.getDefaultToolkit();

Robot robot = new Robot();

final JFrame testFrame = new JFrame(gc);

SwingUtilities.invokeLater(new Runnable() {

public void run() {

JFrame backgroundFrame = new JFrame("Background frame");

backgroundFrame.setUndecorated(true);

JPanel panel = new JPanel();

panel.setBackground(Color.RED);

backgroundFrame.add(panel);

backgroundFrame.setSize(200, 200);

backgroundFrame.setVisible(true);

testFrame.setUndecorated(true);

JPanel p = new JPanel();

p.setOpaque(false);

testFrame.add(p);

AWTUtilities.setWindowOpaque(testFrame, false);

testFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

testFrame.setSize(400, 400);

testFrame.setLocation(0, 0);

testFrame.setVisible(true);

}

});

toolkit.realSync();

//robot.getPixelColor() didn't work right for some reason

BufferedImage capture = robot.createScreenCapture(new Rectangle(100, 100));

int redRGB = Color.RED.getRGB();

if (redRGB != capture.getRGB(10, 10)) {

throw new RuntimeException("Transparent frame is not transparent!");

}

}

private static GraphicsConfiguration getGC() {

GraphicsConfiguration transparencyCapableGC =

GraphicsEnvironment.getLocalGraphicsEnvironment()

.getDefaultScreenDevice().getDefaultConfiguration();

if (!AWTUtilities.isTranslucencyCapable(transparencyCapableGC)) {

transparencyCapableGC = null;

GraphicsEnvironment env =

GraphicsEnvironment.getLocalGraphicsEnvironment();

GraphicsDevice[] devices = env.getScreenDevices();

for (int i = 0; i < devices.length && transparencyCapableGC == null; i++) {

GraphicsConfiguration[] configs = devices[i].getConfigurations();

for (int j = 0; j < configs.length && transparencyCapableGC == null; j++) {

if (AWTUtilities.isTranslucencyCapable(configs[j])) {

transparencyCapableGC = configs[j];

}

}

}

}

return transparencyCapableGC;

}

}