SUGGESTED FIX

http://hg.openjdk.java.net/jdk8/awt/jdk/rev/fd27852f3ea5
                                     

EVALUATION

The problem happens with a pure AWT test.

import java.awt.*;
import javax.swing.*;

public class LocationOnScreenTestAWT {
    public static void main (String ... args) {
        Frame f = new Frame();
        Panel panel = new Panel();
// setBounds() invoaction leads to different results for the label location.
        f.setBounds(0, 0, 100, 100);
        f.add(panel);
        Label js1 = new Label("label 1");
        Label js2 = new Label("label 2");
        panel.add(js1);
        panel.add(js2);
        f.setVisible(true);

        Point p = js2.getLocationOnScreen();

        while (true) {
            try {
                Point tp = js2.getLocationOnScreen();
                if (p.getX()!=tp.getX() || p.getY()!=tp.getY()) {
                    System.err.println("Location on screen: " + js2.getLocationOnScreen());
                    p = tp;
                }
            } catch (Exception e) {
                System.err.println(e.getMessage());
                continue;
            }
        }
    }
}

=====
Output:
Location on screen: java.awt.Point[x=26,y=55]
Location on screen: java.awt.Point[x=51,y=55]
                                     

EVALUATION

I have added Thread.sleep(1000) before invocation of getLocationOnScreen()


$ /export/jdk/jdk1.7.0_05b03/bin/java bug5012888
pinner2.getLocationOnScreen() 1:java.awt.Point[x=5,y=75]
< === 1000
pinner2.getLocationOnScreen() 2:java.awt.Point[x=30,y=75]
pinner2.getLocationOnScreen() 2:java.awt.Point[x=30,y=75]

Looks like we have a time gap before shoiwing the component then we do not throw IllegalComponentStateException.
                                     

EVALUATION

Initially I noticed that the problem is not always reproducible wth jdk7u4b10. So I looked for a timing. It seems there is no delay betwean setVisivble() and a obot click. I have added a delay and  the test passes always now.
                                     

EVALUATION

reproduced on 7u2, please evaluate.