Apple is failing JCK 1.3 test api/java_awt/Layout/GridBagLayoutTests.html[GridBagLayoutTest0003] due to the bug in jdk GridBagLayout resizing code (when downsizing components).

Here's the message from Apple:
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The basic problem is that when the GridBagLayout manager needs to shrink
components it deals poorly with sizes which don't divide into integer
values over a size delta. And since Aqua buttons are somewhat largish we
are hitting this case. The problem being components are then laid out
partly outside their container and Container.getComponentAt(
xCompOrigin, yCompOrigin ) can't find them.

Here is the code:

      diffw = parent.width - r.width;
      if (diffw != 0) {
          weight = 0.0;
          for (i = 0; i < info.width; i++)
              weight += info.weightX[i];
          if (weight > 0.0) {
              for (i = 0; i < info.width; i++) {
                  int dx = (int)(( ((double)diffw) * info.weightX[i]) /
weight); // Here's the problem
                  info.minWidth[i] += dx;
                  r.width += dx;
                  if (info.minWidth[i] < 0) {
                      r.width -= info.minWidth[i];
                      info.minWidth[i] = 0;
                  }
              }
          }
          diffw = parent.width - r.width;
       }

The problem occurs when the 'diffw' value computed in the first line is
negative. The computation for dx truncates non-integer values making,
for example, -12.5 into -12, so that the components are adjusted by
slightly less than needed for them to fit in the container. The final
value of diffw is then negative (-2 in our case), so when the components
are laid out, they are put slightly outside the container, and the JCK
test fails to find them using getComponentAt while passing the
out-of-bounds location.

We hit this problem on MacOS X because the Aqua look and feel provides a
larger preferred size for buttons than is common on other platforms, or
on earlier versions of the Mac OS.
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Here is the testcase that I created to reproduce the failure on solaris:

---------------------------------
import java.awt.*;
import java.io.*;
import java.util.*;


public class test1 {

    static GridBagLayout gridbag1 = null;
    
    public static void main(String[] argv) {
        Frame f = CreateContainer();
        for (int i = 0; i < 1000; i++) {
            f.setSize(new Dimension(50 + (new Random()).nextInt(400), 50 + (new Random().nextInt(400))));
            f.validate();
            Component one = f.getComponent(0);
            Point oLocation = one.getLocation();
            Component oComponent = f.getComponentAt(oLocation.x, oLocation.y);
            Object oObject = (Object) one;
            boolean result = oComponent==oObject;
            if (!result) {
                System.out.println("Component not found at its location");
                System.out.println("oLocation=" + oLocation);
                System.out.println(result);
            }
        }
    }
               
    static Frame CreateContainer() {

        Frame c = new Frame();
        gridbag1 = new GridBagLayout();
        GridBagConstraints constraints = new GridBagConstraints();
        constraints.fill = GridBagConstraints.BOTH;
        constraints.weightx = 1.0;
        c.setLayout(gridbag1);
        Button [] buttons = new Button[16];
        for (int i = 0; i <= 14; i++) {
            buttons[i] = new Button("Button" + i);
            gridbag1.setConstraints(buttons[i], constraints);
            c.add(buttons[i]);
        }
        constraints.weightx = 0.0;
        buttons[15] = new Button("one more");
        gridbag1.setConstraints(buttons[15], constraints);
        c.add(buttons[15]);
        c.setLocation(100, 100);
        c.setVisible(true);
        c.doLayout();
        while (!c.isShowing()) {}
    
        return c;
      
    }
    
}

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Test output under jdk 1.3:

bash-2.00$ /export/tmp/java/jdk1.3/solaris/bin/java test1

Component not found at its location
oLocation=java.awt.Point[x=-1,y=177]
false
Component not found at its location
oLocation=java.awt.Point[x=0,y=0]
false
Component not found at its location
oLocation=java.awt.Point[x=0,y=0]
false
Component not found at its location
oLocation=java.awt.Point[x=0,y=0]
false
Component not found at its location
oLocation=java.awt.Point[x=-1,y=154]
false
Component not found at its location
oLocation=java.awt.Point[x=0,y=0]
false
Component not found at its location
oLocation=java.awt.Point[x=0,y=0]
false
Component not found at its location
oLocation=java.awt.Point[x=0,y=0]
false

and so forth .......
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This needs to be fixed.