A DESCRIPTION OF THE REQUEST :
adjustScrollPositionIfNecessary(JList list, int index, int direction) in BasicListUI should only use y and height when it checks to see if cell is visible. If the cell is wider than the viewport it will always try to scroll.

JUSTIFICATION :
  Customer complains

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Run the test case.
Scroll down to make cell 6 to 13 visible.
Select cell 9.
Use down key to select cell 10.
Cell 10 should be selected without scrolling.
ACTUAL -
Run the test case.
Scroll down to make cell 6 to 13 visible.
Select cell 9.
Use down key to select cell 10.
Cell 10 is selected and cell 3 to 10 is now visible.

---------- BEGIN SOURCE ----------
import java.awt.*;
import java.util.Vector;

import javax.swing.*;

public class Main extends JDialog {
  private static final long serialVersionUID = 7373795962525653313L;

  public static void main(String[] args) {
    try {
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    }
    catch (Exception exception) {
      exception.printStackTrace();
    }
    Main dlg = new Main(null);
    dlg.setVisible(true);
    System.exit(0);
  }

  public Main(Frame owner) {
    super(owner,true);
    Vector<String> strings = new Vector<String>();
    for(int i=1; i<20; i++)
      strings.add(String.format("Long text string %d ..............",i));
    JList jList = new JList(strings);
    JScrollPane jScrollPane = new JScrollPane(jList);
    JPanel jContentPane = new JPanel();
    jContentPane.setLayout(new BorderLayout());
    jContentPane.add(jScrollPane, BorderLayout.CENTER);
    this.setBounds(new Rectangle(0, 0, 100, 200));
    this.setContentPane(jContentPane);
  }
}

---------- END SOURCE ----------