SYNOPSIS
--------
NullPointerException when scrolling horizontally on AWT List

OPERATING SYSTEM
----------------
Probably All platforms.
Test on Solaris x86 and Linux.

FULL JDK VERSION
-------------------
JDK 7 b137.
Reproducible back to at least b32.
Not reproducible using JDK 6.

DESCRIPTION
-----------
NullPointerException occurs when we scrolled horizontally in AWT List.

REPRODUCTION INSTRUCTIONS
-------------------------
1. Compile and launch the attached testcase
2. Drag the scroll bar of AWT List horizontally. You will observe the
   following NullPointerException:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at sun.awt.X11.XListPeer$ListPainter.paint(XListPeer.java:1796)
        at sun.awt.X11.XListPeer$ListPainter.access$000(XListPeer.java:1672)
        at sun.awt.X11.XListPeer.repaint(XListPeer.java:415)
        at sun.awt.X11.XListPeer.scrollHorizontal(XListPeer.java:1492)
        at sun.awt.X11.XListPeer.notifyValue(XListPeer.java:1016)
        at sun.awt.X11.XScrollbar$1.run(XScrollbar.java:112)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
        at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:705)
        at java.awt.EventQueue.access$000(EventQueue.java:101)
        at java.awt.EventQueue$3.run(EventQueue.java:666)
        at java.awt.EventQueue$3.run(EventQueue.java:664)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
        at java.awt.EventQueue$4.run(EventQueue.java:680)
        at java.awt.EventQueue$4.run(EventQueue.java:678)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

TESTCASE
--------
import java.awt.*;

public class ListTest extends Frame {

    ListTest(String[] testStrings){
        List l = new List(testStrings.length, false);
        for (int i=0 ; i < testStrings.length ; i++) {
            l.add(testStrings[i]);
        }
        add(l);
        pack();
        setSize(200, 100);
    }

    public static void main(String[] args){
        String[] strings = {
            "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz",
            "12345678901234567890123456789012345678901234567890"
        };
        ListTest test = new ListTest(strings);
        test.setVisible(true);
    }
}