/*
 * @(#)JList.java	1.74 00/04/06
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package javax.swing;

import java.awt.event.*;
import java.awt.*;

import java.util.Vector;
import java.util.Locale;

import java.beans.*;

import javax.swing.event.*;
import javax.accessibility.*;
import javax.swing.plaf.*;

import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.io.Serializable;


/**
 * A component that allows the user to select one or more objects from a
 * list.  A separate model, <code>ListModel</code>, represents the contents
 * of the list.  It's easy to display an array or vector of objects, using
 * a <code>JList</code> constructor that builds a <code>ListModel</code> 
 * instance for you:
 * <pre>
 * // Create a JList that displays the strings in data[]
 *
 * String[] data = {"one", "two", "three", "four"};
 * JList dataList = new JList(data);
 * 
 * // The value of the JList model property is an object that provides
 * // a read-only view of the data.  It was constructed automatically.
 *
 * for(int i = 0; i < dataList.getModel().getSize(); i++) {
 *     System.out.println(dataList.getModel().getElementAt(i));
 * }
 *
 * // Create a JList that displays the superclass of JList.class.
 * // We store the superclasses in a java.util.Vector.
 *
 * Vector superClasses = new Vector();
 * Class rootClass = javax.swing.JList.class;
 * for(Class cls = rootClass; cls != null; cls = cls.getSuperclass()) {
 *     superClasses.addElement(cls);
 * }
 * JList classList = new JList(superClasses);
 * </pre>
 * <p>
 * <code>JList</code> doesn't support scrolling directly. 
 * To create a scrolling
 * list you make the <code>JList</code> the viewport view of a
 * <code>JScrollPane</code>.  For example:
 * <pre>
 * JScrollPane scrollPane = new JScrollPane(dataList);
 * // Or in two steps:
 * JScrollPane scrollPane = new JScrollPane();
 * scrollPane.getViewport().setView(dataList);
 * </pre>
 * <p>
 * By default the <code>JList</code> selection model allows any
 * combination of items to be selected at a time, using the constant
 * <code>MULTIPLE_INTERVAL_SELECTION</code>.  
 * The selection state is actually managed
 * by a separate delegate object, an instance of
 * <code>ListSelectionModel</code>.
 * However <code>JList</code> provides convenient properties for
 * managing the selection.
 * <pre>
 * String[] data = {"one", "two", "three", "four"};
 * JList dataList = new JList(data);
 *
 * dataList.setSelectedIndex(1);  // select "two"
 * dataList.getSelectedValue();   // returns "two"
 * </pre>
 * <p>
 * The contents of a <code>JList</code> can be dynamic,
 * in other words, the list elements can
 * change value and the size of the list can change after the
 * <code>JList</code> has
 * been created.  The <code>JList</code> observes changes in its model with a
 * <code>swing.event.ListDataListener</code> implementation.  A correct 
 * implementation of <code>ListModel</code> notifies
 * it's listeners each time a change occurs.  The changes are
 * characterized by a <code>swing.event.ListDataEvent</code>, which identifies
 * the range of list indices that have been modified, added, or removed.
 * Simple dynamic-content <code>JList</code> applications can use the
 * <code>DefaultListModel</code> class to store list elements.  This class
 * implements the <code>ListModel</code> interface and provides the
 * <code>java.util.Vector</code> API as well.  Applications that need to 
 * provide custom <code>ListModel</code> implementations can subclass 
 * <code>AbstractListModel</code>, which provides basic 
 * <code>ListDataListener</code> support.  For example:
 * <pre>
 * // This list model has about 2^16 elements.  Enjoy scrolling.
 *
 * <a name="prototype_example">
 * ListModel bigData = new AbstractListModel() {
 *     public int getSize() { return Short.MAX_VALUE; }
 *     public Object getElementAt(int index) { return "Index " + index; }
 * };
 *
 * JList bigDataList = new JList(bigData);
 *
 * // We don't want the JList implementation to compute the width
 * // or height of all of the list cells, so we give it a string
 * // that's as big as we'll need for any cell.  It uses this to
 * // compute values for the fixedCellWidth and fixedCellHeight
 * // properties.
 *
 * bigDataList.setPrototypeCellValue("Index 1234567890");
 * </pre>
 * <p>
 * <code>JList</code> uses a <code>java.awt.Component</code>, provided by 
 * a delegate called the
 * <code>cellRendererer</code>, to paint the visible cells in the list.
 * The cell renderer component is used like a "rubber stamp" to paint
 * each visible row.  Each time the <code>JList</code> needs to paint a cell
 * it asks the cell renderer for the component, moves it into place
 * using <code>setBounds()</code> and then draws it by calling its paint method.
 * The default cell renderer uses a <code>JLabel</code> component to render
 * the string value of each component.   You can substitute your
 * own cell renderer, using code like this:
 * <pre>
 *  // Display an icon and a string for each object in the list.
 *
 * <a name="cellrenderer_example">
 * class MyCellRenderer extends JLabel implements ListCellRenderer {
 *     final static ImageIcon longIcon = new ImageIcon("long.gif");
 *     final static ImageIcon shortIcon = new ImageIcon("short.gif");
 *
 *     // This is the only method defined by ListCellRenderer.
 *     // We just reconfigure the JLabel each time we're called.
 *
 *     public Component getListCellRendererComponent(
 *       JList list,
 *       Object value,            // value to display
 *       int index,               // cell index
 *       boolean isSelected,      // is the cell selected
 *       boolean cellHasFocus)    // the list and the cell have the focus
 *     {
 *         String s = value.toString();
 *         setText(s);
 *         setIcon((s.length() > 10) ? longIcon : shortIcon);
 *   	   if (isSelected) {
 *             setBackground(list.getSelectionBackground());
 *	       setForeground(list.getSelectionForeground());
 *	   }
 *         else {
 *	       setBackground(list.getBackground());
 *	       setForeground(list.getForeground());
 *	   }
 *	   setEnabled(list.isEnabled());
 *	   setFont(list.getFont());
 *         return this;
 *     }
 * }
 *
 * String[] data = {"one", "two", "three", "four"};
 * JList dataList = new JList(data);
 * dataList.setCellRenderer(new MyCellRenderer());
 * </pre>
 * <p>
 * <code>JList</code> doesn't provide any special support for handling double or
 * triple (or N) mouse clicks however it's easy to handle them using
 * a <code>MouseListener</code>.  Use the <code>JList</code> method 
 * <code>locationToIndex()</code> to
 * determine what cell was clicked.  For example:
 * <pre>
 * final JList list = new JList(dataModel);
 * MouseListener mouseListener = new MouseAdapter() {
 *     public void mouseClicked(MouseEvent e) {
 *         if (e.getClickCount() == 2) {
 *             int index = list.locationToIndex(e.getPoint());
 *             System.out.println("Double clicked on Item " + index);
 *          }
 *     }
 * };
 * list.addMouseListener(mouseListener);
 * </pre>
 * Note that in this example the <code>dataList</code> is <code>final</code>
 * because it's referred to by the anonymous <code>MouseListener</code> class.
 * <p>
 * For the keyboard keys used by this component in the standard look and
 * feel (L&F) renditions, see the
 * <a href="doc-files/Key-Index.html#JList">JList</a> key assignments.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases.  The current serialization support is appropriate
 * for short term storage or RMI between applications running the same
 * version of Swing.  A future release of Swing will provide support for
 * long term persistence.
 *
 * <p>
 * See <a href="http://java.sun.com/docs/books/tutorial/uiswing/components/list.html">How to Use Lists</a>
 * in <a href="http://java.sun.com/Series/Tutorial/index.html"><em>The Java Tutorial</em></a>
 * for further documentation.
 * Also see the article <a href="http://java.sun.com/products/jfc/tsc/tech_topics/jlist_1/jlist.html">Advanced JList Programming</a>
 * in <a href="http://java.sun.com/products/jfc/tsc"><em>The Swing Connection</em></a>.
 * <p>
 * @see ListModel
 * @see AbstractListModel
 * @see DefaultListModel
 * @see ListSelectionModel
 * @see DefaultListSelectionModel
 * @see ListCellRenderer
 *
 * @beaninfo
 *   attribute: isContainer false
 * description: A component which allows for the selection of one or more objects from a list.
 *
 * @version 1.74 04/06/00
 * @author Hans Muller
 */
public class JList extends JComponent implements Scrollable, Accessible
{
    /**
     * @see #getUIClassID
     * @see #readObject
     */
    private static final String uiClassID = "ListUI";

    private int fixedCellWidth = -1;
    private int fixedCellHeight = -1;
    private int horizontalScrollIncrement = -1;
    private Object prototypeCellValue;
    private int visibleRowCount = 8;
    private Color selectionForeground;
    private Color selectionBackground;

    private ListSelectionModel selectionModel;
    private ListModel dataModel;
    private ListCellRenderer cellRenderer;
    private ListSelectionListener selectionListener;


    /**
     * Constructs a <code>JList</code> that displays the elements in the
     * specified, non-null model.  All <code>JList</code> constructors
     * delegate to this one.
     * @param dataModel   the data model for this list
     * @exception IllegalArgumentException   if <code>dataModel</code>
     *						is <code>null</code>
     */
    public JList(ListModel dataModel)
    {
        if (dataModel == null) {
            throw new IllegalArgumentException("dataModel must be non null");
        }

        this.dataModel = dataModel;
        selectionModel = createSelectionModel();
        setAutoscrolls(true);
        setOpaque(true);
        updateUI();
    }


    /**
     * Constructs a <code>JList</code> that displays the elements in the specified
     * array.  This constructor just delegates to the <code>ListModel</code>
     * constructor.
     * @param  listData  the array of Objects to be loaded into the data model
     */
    public JList(final Object[] listData)
    {
        this (
            new AbstractListModel() {
                public int getSize() { return listData.length; }
                public Object getElementAt(int i) { return listData[i]; }
            }
        );
    }


    /**
     * Constructs a <code>JList</code> that displays the elements in the specified
     * <code>Vector</code>.  This constructor just delegates to the
     * <code>ListModel</code> constructor.
     * @param  listData  the <code>Vector</code> to be loaded into the data model
     */
    public JList(final Vector listData) {
        this (
            new AbstractListModel() {
                public int getSize() { return listData.size(); }
                public Object getElementAt(int i) { return listData.elementAt(i); }
            }
        );
    }


    /**
     * Constructs a <code>JList</code> with an empty model.
     */
    public JList() {
        this (
            new AbstractListModel() {
              public int getSize() { return 0; }
              public Object getElementAt(int i) { return "No Data Model"; }
            }
        );
    }


    /**
     * Returns the look and feel (L&F) object that renders this component.
     *
     * @return the ListUI object that renders this component
     */
    public ListUI getUI() {
        return (ListUI)ui;
    }


    /**
     * Sets the look and feel (L&F) object that renders this component.
     *
     * @param ui  the ListUI L&F object
     * @see UIDefaults#getUI
     */
    public void setUI(ListUI ui) {
        super.setUI(ui);
    }


    /**
     * Sets the UI property with the "ListUI" from the current default
     * UIFactory.  This method is called by the <code>JList</code> constructor 
     * and to update the list's look and feel at runtime.
     *
     * @see UIManager#getUI
     */
    public void updateUI() {
        setUI((ListUI)UIManager.getUI(this));
        invalidate();
    }


    /**
     * Returns the suffix used to construct the name of the look and feel 
     * (L&F) class used to render this component.
     *
     * @return the string "ListUI"
     * @see JComponent#getUIClassID
     * @see UIDefaults#getUI
     */
    public String getUIClassID() {
        return uiClassID;
    }


    /* -----private-----
     * This method is called by setPrototypeCellValue and setCellRenderer
     * to update the fixedCellWidth and fixedCellHeight properties from the
     * current value of prototypeCellValue (if it's non null).
     * <p>
     * This method sets fixedCellWidth and fixedCellHeight but does <b>not</b>
     * generate PropertyChangeEvents for them.
     *
     * @see #setPrototypeCellValue
     * @see #setCellRenderer
     */
    private void updateFixedCellSize()
    {
        ListCellRenderer cr = getCellRenderer();
        Object value = getPrototypeCellValue();

        if ((cr != null) && (value != null)) {
            Component c = cr.getListCellRendererComponent(this, value, 0, false, false);

            /* The ListUI implementation will add Component c to its private
             * CellRendererPane however we can't assume that's already
             * been done here.  So we temporarilty set the one "inherited"
             * property that may affect the renderer components preferred size:
             * its font.
             */
            Font f = c.getFont();
            c.setFont(getFont());

            Dimension d = c.getPreferredSize();
            fixedCellWidth = d.width;
            fixedCellHeight = d.height;

            c.setFont(f);
        }
    }


    /**
     * Returns the cell width of the "prototypical cell" -- a cell used
     * for the calculation of cell widths, because it has the same value
     * as all other list items.
     *
     * @return the value of the <code>prototypeCellValue</code> property
     * @see #setPrototypeCellValue
     */
    public Object getPrototypeCellValue() {
        return prototypeCellValue;
    }

    /**
     * Computes the <code>fixedCellWidth</code> and 
     * <code>fixedCellHeight</code> properties
     * by configuring the <code>cellRenderer</code> to index equals
     * zero for the specified value and then computing the renderer
     * component's preferred size.  These properties are useful when the
     * list is too long to allow <code>JList</code> to compute the
     * width/height of each cell and there is a single cell value that is
     * known to occupy as much space as any of the others.
     * <p>
     * Note that we do set the <code>fixedCellWidth</code> and 
     * <code>fixedCellHeight</code> properties here but only a 
     * <code>prototypeCellValue PropertyChangeEvent</code> is fired.
     * <p>
     * To see an example which sets this property, 
     * see the <a href = #prototype_example>class description</a> above.
     * <p>
     * The default value of this property is <code>null</code>.
     * <p>
     * This is a JavaBeans bound property.  
     *
     * @param prototypeCellValue  the value on which to base
     *				<code>fixedCellWidth</code> and
     * 				<code>fixedCellHeight</code>
     * @see #getPrototypeCellValue
     * @see #setFixedCellWidth
     * @see #setFixedCellHeight
     * @see JComponent#addPropertyChangeListener
     * @beaninfo
     *       bound: true
     *   attribute: visualUpdate true
     * description: The cell prototype value, used to compute cell width and height.
     */
    public void setPrototypeCellValue(Object prototypeCellValue) {
        Object oldValue = this.prototypeCellValue;
        this.prototypeCellValue = prototypeCellValue;

        /* If the cellRenderer has changed and prototypeCellValue
         * was set, then recompute fixedCellWidth and fixedCellHeight.
         */

        if ((prototypeCellValue != null) && !prototypeCellValue.equals(oldValue)) {
            updateFixedCellSize();
        }

        firePropertyChange("prototypeCellValue", oldValue, prototypeCellValue);
    }


    /**
     * Returns the fixed cell width value -- the value specified by setting
     * the <code>fixedCellWidth</code> property, rather than that calculated
     * from the list elements.
     *
     * @return the fixed cell width
     * @see #setFixedCellWidth
     */
    public int getFixedCellWidth() {
        return fixedCellWidth;
    }

    /**
     * Sets the width of every cell in the list.  If <code>width</code> is -1,
     * cell widths are computed by applying <code>getPreferredSize</code>
     * to the <code>cellRenderer</code> component for each list element.
     * <p>
     * The default value of this property is -1.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param width   the width, in pixels, for all cells in this list
     * @see #getPrototypeCellValue
     * @see #setFixedCellWidth
     * @see JComponent#addPropertyChangeListener
     * @beaninfo
     *       bound: true
     *   attribute: visualUpdate true
     * description: Defines a fixed cell width when greater than zero.
     */
    public void setFixedCellWidth(int width) {
        int oldValue = fixedCellWidth;
        fixedCellWidth = width;
        firePropertyChange("fixedCellWidth", oldValue, fixedCellWidth);
    }


    /**
     * Returns the fixed cell height value -- the value specified by setting
     * the <code>fixedCellHeight</code> property,
     * rather than that calculated from the list elements.
     * 
     * @return the fixed cell height, in pixels 
     * @see #setFixedCellHeight
     */
    public int getFixedCellHeight() {
        return fixedCellHeight;
    }

    /**
     * Sets the height of every cell in the list.  If <code>height</code>
     * is -1, cell
     * heights are computed by applying <code>getPreferredSize</code>
     * to the <code>cellRenderer</code> component for each list element.
     * <p>
     * The default value of this property is -1.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param height an integer giving the height, in pixels, for all cells 
     *        in this list
     * @see #getPrototypeCellValue
     * @see #setFixedCellWidth
     * @see JComponent#addPropertyChangeListener
     * @beaninfo
     *       bound: true
     *   attribute: visualUpdate true
     * description: Defines a fixed cell height when greater than zero.
     */
    public void setFixedCellHeight(int height) {
        int oldValue = fixedCellHeight;
        fixedCellHeight = height;
        firePropertyChange("fixedCellHeight", oldValue, fixedCellHeight);
    }


    /**
     * Returns the object that renders the list items.
     *
     * @return the <code>ListCellRenderer</code>
     * @see #setCellRenderer
     */
    public ListCellRenderer getCellRenderer() {
        return cellRenderer;
    }

    /**
     * Sets the delegate that's used to paint each cell in the list.  If
     * <code>prototypeCellValue</code> was set then the 
     * <code>fixedCellWidth</code> and <code>fixedCellHeight</code>
     * properties are set as well.  Only one <code>PropertyChangeEvent</code>
     * is generated however - for the <code>cellRenderer</code> property.
     * <p>
     * The default value of this property is provided by the ListUI
     * delegate, i.e. by the look and feel implementation.
     * <p>
     * To see an example which sets the cell renderer, 
     * see the <a href = #cellrenderer_example>class description</a> above.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param cellRenderer the <code>ListCellRenderer</code>
     * 				that paints list cells
     * @see #getCellRenderer
     * @beaninfo
     *       bound: true
     *   attribute: visualUpdate true
     * description: The component used to draw the cells.
     */
    public void setCellRenderer(ListCellRenderer cellRenderer) {
        ListCellRenderer oldValue = this.cellRenderer;
        this.cellRenderer = cellRenderer;

        /* If the cellRenderer has changed and prototypeCellValue
         * was set, then recompute fixedCellWidth and fixedCellHeight.
         */
        if ((cellRenderer != null) && !cellRenderer.equals(oldValue)) {
            updateFixedCellSize();
        }

        firePropertyChange("cellRenderer", oldValue, cellRenderer);
    }


    /**
     * Returns the selection foreground color.
     *
     * @return the <code>Color</code> object for the foreground property
     * @see #setSelectionForeground
     * @see #setSelectionBackground
     */
    public Color getSelectionForeground() {
        return selectionForeground;
    }


    /**
     * Sets the foreground color for selected cells.  Cell renderers
     * can use this color to render text and graphics for selected
     * cells.
     * <p>
     * The default value of this property is defined by the look
     * and feel implementation.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param selectionForeground  the <code>Color</code> to use in the foreground
     *                             for selected list items
     * @see #getSelectionForeground
     * @see #setSelectionBackground
     * @see #setForeground
     * @see #setBackground
     * @see #setFont
     * @beaninfo
     *       bound: true
     *   attribute: visualUpdate true
     * description: The foreground color of selected cells.
     */
    public void setSelectionForeground(Color selectionForeground) {
        Color oldValue = this.selectionForeground;
        this.selectionForeground = selectionForeground;
        firePropertyChange("selectionForeground", oldValue, selectionForeground);
    }


    /**
     * Returns the background color for selected cells.
     *
     * @return the <code>Color</code> used for the background of
     * selected list items
     * @see #setSelectionBackground
     * @see #setSelectionForeground
     */
    public Color getSelectionBackground() {
        return selectionBackground;
    }


    /**
     * Sets the background color for selected cells.  Cell renderers
     * can use this color to the fill selected cells.
     * <p>
     * The default value of this property is defined by the look
     * and feel implementation.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param selectionBackground  the <code>Color</code> to use for the 
     *                             background of selected cells
     * @see #getSelectionBackground
     * @see #setSelectionForeground
     * @see #setForeground
     * @see #setBackground
     * @see #setFont
     * @beaninfo
     *       bound: true
     *   attribute: visualUpdate true
     * description: The background color of selected cells.
     */
    public void setSelectionBackground(Color selectionBackground) {
        Color oldValue = this.selectionBackground;
        this.selectionBackground = selectionBackground;
        firePropertyChange("selectionBackground", oldValue, selectionBackground);
    }


    /**
     * Returns the preferred number of visible rows.
     *
     * @return an integer indicating the preferred number of rows to display
     *         without using a scroll bar
     * @see #setVisibleRowCount
     */
    public int getVisibleRowCount() {
        return visibleRowCount;
    }

    /**
     * Sets the preferred number of rows in the list that can be displayed
     * without a scollbar, as determined by the nearest
     * <code>JViewport</code> ancestor, if any.
     * The value of this property only affects the value of
     * the <code>JList</code>'s <code>preferredScrollableViewportSize</code>.
     * <p>
     * The default value of this property is 8.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param visibleRowCount  an integer specifying the preferred number of
     *                         visible rows
     * @see #getVisibleRowCount
     * @see JComponent#getVisibleRect
     * @see JViewport
     * @beaninfo
     *       bound: true
     *   attribute: visualUpdate true
     * description: The preferred number of cells that can be displayed without a scroll bar.
     */
    public void setVisibleRowCount(int visibleRowCount) {
        int oldValue = this.visibleRowCount;
        this.visibleRowCount = Math.max(0, visibleRowCount);
        firePropertyChange("visibleRowCount", oldValue, visibleRowCount);
    }


    /**
     * Returns the index of the cell in the upper left corner of the 
     * <code>JList</code>
     * or -1 if nothing is visible or the list is empty.  Note that this
     * cell may only be partially visible.
     *
     * @return the index of the first visible cell
     * @see #getLastVisibleIndex
     * @see JComponent#getVisibleRect
     */
    public int getFirstVisibleIndex() {
        Point visibleUL = getVisibleRect().getLocation();
        return locationToIndex(visibleUL);
    }


    /**
     * Returns the index of the cell in the lower right corner of the 
     * <code>JList</code>
     * or -1 if nothing is visible or the list is empty.  Note that this
     * cell may only be partially visible.
     *
     * @return the index of the last visible cell
     * @see #getLastVisibleIndex
     * @see JComponent#getVisibleRect
     */
    public int getLastVisibleIndex() {
        Rectangle r = getVisibleRect();
        Point visibleLR = new Point((r.x + r.width) - 1, (r.y + r.height) - 1);
        return locationToIndex(visibleLR);
    }


    /**
     * Scrolls the viewport to make the specified cell completely visible.
     * Note, for this method to work, the <code>JList</code> must be
     * displayed within a <code>JViewport</code>.
     *
     * @param index  the index of the cell to make visible
     * @see JComponent#scrollRectToVisible
     * @see #getVisibleRect
     */
    public void ensureIndexIsVisible(int index) {
        Rectangle cellBounds = getCellBounds(index, index);
        if (cellBounds != null) {
            scrollRectToVisible(cellBounds);
        }
    }


    /**
     * --- ListUI Delegations ---
     */


    /**
     * Converts a point in <code>JList</code> coordinates to the index
     * of the cell at that location.  Returns -1 if there's no
     * cell at the specified location.
     *
     * @param location the coordinates of the cell, relative to
     *			<code>JList</code>
     * @return an integer -- the index of the cell at the given location, or -1.
     */
    public int locationToIndex(Point location) {
        ListUI ui = getUI();
        return (ui != null) ? ui.locationToIndex(this, location) : -1;
    }


    /**
     * Returns the origin of the specified item in <code>JList</code>
     * coordinates. Returns <code>null</code> if <code>index</code> isn't valid.
     *
     * @param index the index of the <code>JList</code> cell
     * @return the origin of the index'th cell
     */
    public Point indexToLocation(int index) {
        ListUI ui = getUI();
        return (ui != null) ? ui.indexToLocation(this, index) : null;
    }


    /**
     * Returns the bounds of the specified range of items in <code>JList</code>
     * coordinates. Returns <code>null</code> if index isn't valid.
     *
     * @param index0  the index of the first <code>JList</code> cell in the range
     * @param index1  the index of the last <code>JList</code> cell in the range
     * @return the bounds of the indexed cells in pixels
     */
    public Rectangle getCellBounds(int index0, int index1) {
        ListUI ui = getUI();
        return (ui != null) ? ui.getCellBounds(this, index0, index1) : null;
    }


    /**
     * --- ListModel Support ---
     */


    /**
     * Returns the data model that holds the list of items displayed
     * by the <code>JList</code> component.
     *
     * @return the <code>ListModel</code> that provides the displayed
     *				list of items
     * @see #setModel
     */
    public ListModel getModel() {
        return dataModel;
    }

    /**
     * Sets the model that represents the contents or "value" of the
     * list and clears the list selection after notifying
     * <code>PropertyChangeListeners</code>.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param model  the <code>ListModel</code> that provides the
     *						list of items for display
     * @exception IllegalArgumentException  if <code>model</code> is 
     *						<code>null</code>
     * @see #getModel
     * @beaninfo
     *       bound: true
     *   attribute: visualUpdate true
     * description: The object that contains the data to be drawn by this JList.
     */
    public void setModel(ListModel model) {
        if (model == null) {
            throw new IllegalArgumentException("model must be non null");
        }
        ListModel oldValue = dataModel;
        dataModel = model;
        firePropertyChange("model", oldValue, dataModel);
        clearSelection();
    }


    /**
     * Constructs a <code>ListModel</code> from an array of objects and then
     * applies <code>setModel</code> to it.
     *
     * @param listData an array of Objects containing the items to display
     *                 in the list
     * @see #setModel
     */
    public void setListData(final Object[] listData) {
        setModel (
            new AbstractListModel() {
                public int getSize() { return listData.length; }
                public Object getElementAt(int i) { return listData[i]; }
            }
        );
    }


    /**
     * Constructs a <code>ListModel</code> from a <code>Vector</code> and then
     * applies <code>setModel</code> to it.
     *
     * @param listData a <code>Vector</code> containing the items to
     *						display in the list
     * @see #setModel
     */
    public void setListData(final Vector listData) {
        setModel (
            new AbstractListModel() {
                public int getSize() { return listData.size(); }
                public Object getElementAt(int i) { return listData.elementAt(i); }
            }
        );
    }


    /**
     * --- ListSelectionModel delegations and extensions ---
     */


    /**
     * Returns an instance of <code>DefaultListSelectionModel</code>.  This
     * method is used by the constructor to initialize the
     * <code>selectionModel</code> property.
     *
     * @return the <code>ListSelectionModel</code> used by this
     *					<code>JList</code>.
     * @see #setSelectionModel
     * @see DefaultListSelectionModel
     */
    protected ListSelectionModel createSelectionModel() {
        return new DefaultListSelectionModel();
    }


    /**
     * Returns the value of the current selection model. The selection
     * model handles the task of making single selections, selections
     * of contiguous ranges, and non-contiguous selections.
     *
     * @return the <code>ListSelectionModel</code> that implements
     *					list selections
     * @see #setSelectionModel
     * @see ListSelectionModel
     */
    public ListSelectionModel getSelectionModel() {
        return selectionModel;
    }


    /**
     * Notifies <code>JList</code> <code>ListSelectionListener</code>s that
     * the selection model has changed.  It's used to forward
     * <code>ListSelectionEvents</code> from the <code>selectionModel</code>
     * to the <code>ListSelectionListener</code>s added directly to the
     * <code>JList</code>.
     * @param firstIndex   the first selected index
     * @param lastIndex	   the last selected index
     * @param isAdjusting  true if multiple changes are being made
     *
     * @see #addListSelectionListener
     * @see #removeListSelectionListener
     * @see EventListenerList
     */
    protected void fireSelectionValueChanged(int firstIndex, int lastIndex,
                                             boolean isAdjusting)
    {
        Object[] listeners = listenerList.getListenerList();
        ListSelectionEvent e = null;

        for (int i = listeners.length - 2; i >= 0; i -= 2) {
            if (listeners[i] == ListSelectionListener.class) {
                if (e == null) {
                    e = new ListSelectionEvent(this, firstIndex, lastIndex,
                                               isAdjusting);
                }
                ((ListSelectionListener)listeners[i+1]).valueChanged(e);
            }
        }
    }


    /* A ListSelectionListener that forwards ListSelectionEvents from 
     * the selectionModel to the JList ListSelectionListeners.  The 
     * forwarded events only differ from the originals in that their 
     * source is the JList instead of the selectionModel itself.
     */
    private class ListSelectionHandler implements ListSelectionListener, Serializable 
    {
	public void valueChanged(ListSelectionEvent e) {
	    fireSelectionValueChanged(e.getFirstIndex(),
				      e.getLastIndex(),
				      e.getValueIsAdjusting());
	}
    }
	

    /**
     * Adds a listener to the list that's notified each time a change
     * to the selection occurs.  Listeners added directly to the
     * <code>JList</code>
     * will have their <code>ListSelectionEvent.getSource() == 
     * this JList</code>
     * (instead of the <code>ListSelectionModel</code>).
     *
     * @param listener the <code>ListSelectionListener</code> to add
     * @see #getSelectionModel
     */
    public void addListSelectionListener(ListSelectionListener listener) 
    {
        if (selectionListener == null) {
            selectionListener = new ListSelectionHandler();
            getSelectionModel().addListSelectionListener(selectionListener);
        }

        listenerList.add(ListSelectionListener.class, listener);
    }


    /**
     * Removes a listener from the list that's notified each time a
     * change to the selection occurs.
     *
     * @param listener the <code>ListSelectionListener</code> to remove
     * @see #addListSelectionListener
     * @see #getSelectionModel
     */
    public void removeListSelectionListener(ListSelectionListener listener) {
        listenerList.remove(ListSelectionListener.class, listener);
    }


    /**
     * Sets the <code>selectionModel</code> for the list to a
     * non-<code>null</code> <code>ListSelectionModel</code>
     * implementation. The selection model handles the task of making single
     * selections, selections of contiguous ranges, and non-contiguous
     * selections.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param selectionModel  the <code>ListSelectionModel</code> that
     *				implements the selections
     * @exception IllegalArgumentException   if <code>selectionModel</code>
     * 						is <code>null</code>
     * @see #getSelectionModel
     * @beaninfo
     *       bound: true
     * description: The selection model, recording which cells are selected.
     */
    public void setSelectionModel(ListSelectionModel selectionModel) {
        if (selectionModel == null) {
            throw new IllegalArgumentException("selectionModel must be non null");
        }

        /* Remove the forwarding ListSelectionListener from the old
         * selectionModel, and add it to the new one, if neccessary.
         */
        if (selectionListener != null) {
            this.selectionModel.removeListSelectionListener(selectionListener);
            selectionModel.addListSelectionListener(selectionListener);
        }

        ListSelectionModel oldValue = this.selectionModel;
        this.selectionModel = selectionModel;
        firePropertyChange("selectionModel", oldValue, selectionModel);
    }


    /**
     * Determines whether single-item or multiple-item
     * selections are allowed.
     * The following <code>selectionMode</code> values are allowed:
     * <ul>
     * <li> <code>SINGLE_SELECTION</code>
     *   Only one list index can be selected at a time.  In this
     *   mode the <code>setSelectionInterval</code> and 
     *   <code>addSelectionInterval</code>
     *   methods are equivalent, and only the second index
     *   argument is used.
     * <li> <code>SINGLE_INTERVAL_SELECTION</code>
     *   One contiguous index interval can be selected at a time.
     *   In this mode <code>setSelectionInterval</code> and 
     *   <code>addSelectionInterval</code>
     *   are equivalent.
     * <li> <code>MULTIPLE_INTERVAL_SELECTION</code>
     *   In this mode, there's no restriction on what can be selected.
     *   This is the default.
     * </ul>
     *
     * @param selectionMode an integer specifying the type of selections 
     *                         that are permissible
     * @see #getSelectionMode
     * @beaninfo
     * description: The selection mode.
     *        enum: SINGLE_SELECTION            ListSelectionModel.SINGLE_SELECTION
     *              SINGLE_INTERVAL_SELECTION   ListSelectionModel.SINGLE_INTERVAL_SELECTION
     *              MULTIPLE_INTERVAL_SELECTION ListSelectionModel.MULTIPLE_INTERVAL_SELECTION
     */
    public void setSelectionMode(int selectionMode) {
        getSelectionModel().setSelectionMode(selectionMode);
    }

    /**
     * Returns whether single-item or multiple-item selections are allowed.
     *
     * @return the value of the <code>selectionMode</code> property
     * @see #setSelectionMode
     */
    public int getSelectionMode() {
        return getSelectionModel().getSelectionMode();
    }


    /**
     * Returns the first index argument from the most recent 
     * <code>addSelectionModel</code> or <code>setSelectionInterval</code> call.
     * This is a convenience method that just delegates to the
     * <code>selectionModel</code>.
     *
     * @return the index that most recently anchored an interval selection
     * @see ListSelectionModel#getAnchorSelectionIndex
     * @see #addSelectionInterval
     * @see #setSelectionInterval
     * @see #addListSelectionListener
     */
    public int getAnchorSelectionIndex() {
        return getSelectionModel().getAnchorSelectionIndex();
    }


    /**
     * Returns the second index argument from the most recent
     * <code>addSelectionInterval</code> or <code>setSelectionInterval</code>
     * call.
     * This is a convenience method that just  delegates to the 
     * <code>selectionModel</code>.
     *
     * @return the index that most recently ended a interval selection
     * @see ListSelectionModel#getLeadSelectionIndex
     * @see #addSelectionInterval
     * @see #setSelectionInterval
     * @see #addListSelectionListener
     * @beaninfo
     * description: The lead selection index.
     */
    public int getLeadSelectionIndex() {
        return getSelectionModel().getLeadSelectionIndex();
    }


    /**
     * Returns the smallest selected cell index.
     * This is a convenience method that just delegates to the 
     * <code>selectionModel</code>.
     *
     * @return the smallest selected cell index
     * @see ListSelectionModel#getMinSelectionIndex
     * @see #addListSelectionListener
     */
    public int getMinSelectionIndex() {
        return getSelectionModel().getMinSelectionIndex();
    }


    /**
     * Returns the largest selected cell index.
     * This is a convenience method that just delegates to the 
     * <code>selectionModel</code>.
     *
     * @return the largest selected cell index
     * @see ListSelectionModel#getMaxSelectionIndex
     * @see #addListSelectionListener
     */
    public int getMaxSelectionIndex() {
        return getSelectionModel().getMaxSelectionIndex();
    }


    /**
     * Returns true if the specified index is selected.
     * This is a convenience method that just delegates to the 
     * <code>selectionModel</code>.
     *
     * @param index index to be queried for selection state
     * @return true if the specified index is selected
     * @see ListSelectionModel#isSelectedIndex
     * @see #setSelectedIndex
     * @see #addListSelectionListener
     */
    public boolean isSelectedIndex(int index) {
        return getSelectionModel().isSelectedIndex(index);
    }


    /**
     * Returns true if nothing is selected.
     * This is a convenience method that just delegates to the 
     * <code>selectionModel</code>.
     *
     * @return true if nothing is selected
     * @see ListSelectionModel#isSelectionEmpty
     * @see #clearSelection
     * @see #addListSelectionListener
     */
    public boolean isSelectionEmpty() {
        return getSelectionModel().isSelectionEmpty();
    }


    /**
     * Clears the selection - after calling this method 
     * <code>isSelectionEmpty</code> will return true.
     * This is a convenience method that just delegates to the 
     * <code>selectionModel</code>.
     *
     * @see ListSelectionModel#clearSelection
     * @see #isSelectionEmpty
     * @see #addListSelectionListener
     */
    public void clearSelection() {
        getSelectionModel().clearSelection();
    }


    /**
     * Selects the specified interval.  Both the anchor and lead indices are
     * included.  It's not neccessary for anchor to be less than lead.
     * This is a convenience method that just delegates to the 
     * <code>selectionModel</code>.
     *
     * @param anchor the first index to select
     * @param lead the last index to select
     * @see ListSelectionModel#setSelectionInterval
     * @see #addSelectionInterval
     * @see #removeSelectionInterval
     * @see #addListSelectionListener
     */
    public void setSelectionInterval(int anchor, int lead) {
        getSelectionModel().setSelectionInterval(anchor, lead);
    }


    /**
     * Sets the selection to be the union of the specified interval with current
     * selection.  Both the anchor and lead indices are
     * included.  It's not neccessary for anchor to be less than lead.
     * This is a convenience method that just delegates to the 
     * <code>selectionModel</code>.
     *
     * @param anchor the first index to add to the selection
     * @param lead the last index to add to the selection
     * @see ListSelectionModel#addSelectionInterval
     * @see #setSelectionInterval
     * @see #removeSelectionInterval
     * @see #addListSelectionListener
     */
    public void addSelectionInterval(int anchor, int lead) {
        getSelectionModel().addSelectionInterval(anchor, lead);
    }


    /**
     * Sets the selection to be the set difference of the specified interval
     * and the current selection.  Both the anchor and lead indices are
     * removed.  It's not neccessary for anchor to be less than lead.
     * This is a convenience method that just delegates to the 
     * <code>selectionModel</code>.
     *
     * @param anchor the first index to remove from the selection
     * @param lead the last index to remove from the selection
     * @see ListSelectionModel#removeSelectionInterval
     * @see #setSelectionInterval
     * @see #addSelectionInterval
     * @see #addListSelectionListener
     */
    public void removeSelectionInterval(int index0, int index1) {
        getSelectionModel().removeSelectionInterval(index0, index1);
    }


    /**
     * Sets the data model's <code>isAdjusting</code> property to true,
     * so that a single event will be generated when all of the selection
     * events have finished (for example, when the mouse is being
     * dragged over the list in selection mode).
     *
     * @param b the boolean value for the property value
     * @see ListSelectionModel#setValueIsAdjusting
     */
    public void setValueIsAdjusting(boolean b) {
        getSelectionModel().setValueIsAdjusting(b);
    }


    /**
     * Returns the value of the data model's <code>isAdjusting</code> property.
     * This value is true if multiple changes are being made.
     *
     * @return true if multiple selection-changes are occurring, as
     *         when the mouse is being dragged over the list
     * @see ListSelectionModel#getValueIsAdjusting
     */
    public boolean getValueIsAdjusting() {
        return getSelectionModel().getValueIsAdjusting();
    }


    /**
     * Returns an array of all of the selected indices in increasing
     * order.
     *
     * @return all of the selected indices, in increasing order
     * @see #removeSelectionInterval
     * @see #addListSelectionListener
     */
    public int[] getSelectedIndices() {
        ListSelectionModel sm = getSelectionModel();
        int iMin = sm.getMinSelectionIndex();
        int iMax = sm.getMaxSelectionIndex();

        if ((iMin < 0) || (iMax < 0)) {
            return new int[0];
        }

        int[] rvTmp = new int[1+ (iMax - iMin)];
        int n = 0;
        for(int i = iMin; i <= iMax; i++) {
            if (sm.isSelectedIndex(i)) {
                rvTmp[n++] = i;
            }
        }
        int[] rv = new int[n];
        System.arraycopy(rvTmp, 0, rv, 0, n);
        return rv;
    }


    /**
     * Selects a single cell.
     *
     * @param index the index of the one cell to select
     * @see ListSelectionModel#setSelectionInterval
     * @see #isSelectedIndex
     * @see #addListSelectionListener
     * @beaninfo
     * description: The index of the selected cell.
     */
    public void setSelectedIndex(int index) {
        getSelectionModel().setSelectionInterval(index, index);
    }


    /**
     * Selects a set of cells.
     *
     * @param indices an array of the indices of the cells to select
     * @see ListSelectionModel#addSelectionInterval
     * @see #isSelectedIndex
     * @see #addListSelectionListener
     */
    public void setSelectedIndices(int[] indices) {
        ListSelectionModel sm = getSelectionModel();
        sm.clearSelection();
        for(int i = 0; i < indices.length; i++) {
            sm.addSelectionInterval(indices[i], indices[i]);
        }
    }


    /**
     * Returns an array of the values for the selected cells.
     * The returned values are sorted in increasing index order.
     *
     * @return the selected values
     * @see #isSelectedIndex
     * @see #getModel
     * @see #addListSelectionListener
     */
    public Object[] getSelectedValues() {
        ListSelectionModel sm = getSelectionModel();
        ListModel dm = getModel();

        int iMin = sm.getMinSelectionIndex();
        int iMax = sm.getMaxSelectionIndex();

        if ((iMin < 0) || (iMax < 0)) {
            return new Object[0];
        }

        Object[] rvTmp = new Object[1+ (iMax - iMin)];
        int n = 0;
        for(int i = iMin; i <= iMax; i++) {
            if (sm.isSelectedIndex(i)) {
                rvTmp[n++] = dm.getElementAt(i);
            }
        }
        Object[] rv = new Object[n];
        System.arraycopy(rvTmp, 0, rv, 0, n);
        return rv;
    }


    /**
     * Returns the first selected index; returns -1 if there is no
     * selected item.
     *
     * @return the value of <code>getMinSelectionIndex</code>
     * @see #getMinSelectionIndex
     * @see #addListSelectionListener
     */
    public int getSelectedIndex() {
        return getMinSelectionIndex();
    }


    /**
     * Returns the first selected value, or <code>null</code> if the 
     * selection is empty.
     *
     * @return the first selected value
     * @see #getMinSelectionIndex
     * @see #getModel
     * @see #addListSelectionListener
     */
    public Object getSelectedValue() {
        int i = getMinSelectionIndex();
        return (i == -1) ? null : getModel().getElementAt(i);
    }


    // PENDING(hmuller) this should move to BasicComboBoxUI
    /**
     * Selects the specified object from the list.
     *
     * @param anObject      the object to select     
     * @param shouldScroll  true if the list should scroll to display
     *                      the selected object, if one exists; otherwise false
     */
    public void setSelectedValue(Object anObject,boolean shouldScroll) {
        if(anObject == null)
            setSelectedIndex(-1);
        else if(!anObject.equals(getSelectedValue())) {
            int i,c;
            ListModel dm = getModel();
            for(i=0,c=dm.getSize();i<c;i++)
                if(anObject.equals(dm.getElementAt(i))){
                    setSelectedIndex(i);
                    if(shouldScroll)
                        ensureIndexIsVisible(i);
                    repaint();  /** FIX-ME setSelectedIndex does not redraw all the time with the basic l&f**/
                    return;
                }
            setSelectedIndex(-1);
        }
        repaint(); /** FIX-ME setSelectedIndex does not redraw all the time with the basic l&f**/
    }



    /**
     * --- The Scrollable Implementation ---
     */

    private void checkScrollableParameters(Rectangle visibleRect, int orientation) {
	if (visibleRect == null) {
	    throw new IllegalArgumentException("visibleRect must be non-null");
	}
        switch (orientation) {
        case SwingConstants.VERTICAL:
        case SwingConstants.HORIZONTAL:
            break;
        default:
            throw new IllegalArgumentException("orientation must be one of: VERTICAL, HORIZONTAL");
        }
    }


    /**
     * Computes the size of the viewport needed to display 
     * <code>visibleRowCount</code>
     * rows.  This is trivial if 
     * <code>fixedCellWidth</code> and <code>fixedCellHeight</code>
     * were specified.  Note that they can be specified implicitly with
     * the <code>prototypeCellValue</code> property.  
     * If <code>fixedCellWidth</code> wasn't specified,
     * it's computed by finding the widest list element.  
     * If <code>fixedCellHeight</code>
     * wasn't specified then we resort to heuristics:
     * <ul>
     * <li>
     * If the model isn't empty we just multiply the height of the first row
     * by <code>visibleRowCount</code>.
     * <li>
     * If the model is empty, (<code>JList.getModel().getSize() == 0</code>),
     * then we just allocate 16 pixels per visible row, and 256 pixels
     * for the width (unless <code>fixedCellWidth</code> was set),
     * and hope for the best.
     * </ul>
     *
     * @return a dimension containing the size of the viewport needed
     *		to display <code>visibleRowCount</code> rows
     * @see #getPreferredScrollableViewportSize
     * @see #setPrototypeCellValue
     */
    public Dimension getPreferredScrollableViewportSize()
    {
        Insets insets = getInsets();
        int dx = insets.left + insets.right;
        int dy = insets.top + insets.bottom;

        int visibleRowCount = getVisibleRowCount();
        int fixedCellWidth = getFixedCellWidth();
        int fixedCellHeight = getFixedCellHeight();

        if ((fixedCellWidth > 0) && (fixedCellHeight > 0)) {
            int width = fixedCellWidth + dx;
            int height = (visibleRowCount * fixedCellHeight) + dy;
            return new Dimension(width, height);
        }
        else if (getModel().getSize() > 0) {
            int width = getPreferredSize().width;
            Rectangle r = getCellBounds(0, 0);
            int height = (visibleRowCount * r.height) + dy;
            return new Dimension(width, height);
        }
        else {
            fixedCellWidth = (fixedCellWidth > 0) ? fixedCellWidth : 256;
            fixedCellHeight = (fixedCellHeight > 0) ? fixedCellHeight : 16;
            return new Dimension(fixedCellWidth, fixedCellHeight * visibleRowCount);
        }
    }


    /**
     * Returns the distance to scroll to expose the next or previous
     * row (for vertical scrolling) or character (for horizontal scrolling).
     * For horizontal scrolling: return the lists font size or 1 if the font
     * is <code>null</code>.
     * We're using the font size instead of the width of some canonical string,
     * e.g. "m", because it's cheaper.
     * <p>
     * For verticaL scrolling: if we're scrolling downwards (<code>direction</code> is
     * greater than 0), and the first row is completely visible with respect
     * to <code>visibleRect</code>, then return its height.  If
     * we're scrolling downwards and the first row is only partially visible,
     * return the height of the visible part of the first row.  Similarly
     * if we're scrolling upwards we return the height of the row above
     * the first row, unless the first row is partially visible.
     * <p>
     * Note that the value of <code>visibleRect</code> must be the equal to 
     * <code>this.getVisibleRect()</code>.
     *
     * @param visibleRect  the visible rectangle
     * @param orientation  HORIZONTAL or VERTICAL  
     * @param direction    if <= 0, then scroll UP; if > 0, then scroll DOWN
     * @return the distance, in pixels, to scroll to expose the
     *			next or previous unit
     * @see Scrollable#getScrollableUnitIncrement
     * @throws IllegalArgumentException  if visibleRect is <code>null<code>, or
     *         orientation isn't one of SwingConstants.VERTICAL,
     *         SwingConstants.HORIZONTAL.
     * 
     */
    public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction)
    {
	checkScrollableParameters(visibleRect, orientation);

        if (orientation == SwingConstants.HORIZONTAL) {
	    Font f = getFont();
	    return (f != null) ? f.getSize() : 1;
	}
        else {
            int row = getFirstVisibleIndex();

            if (row == -1) {
                return 0;
            }
            else {
                /* Scroll Down */
                if (direction > 0) {
                    Rectangle r = getCellBounds(row, row);
                    return (r == null) ? 0 : r.height - (visibleRect.y - r.y);
                }
                /* Scroll Up */
                else {
                    Rectangle r = getCellBounds(row, row);

                    /* The first row is completely visible and it's row 0.
                     * We're done.
                     */
                    if ((r.y == visibleRect.y) && (row == 0))  {
                        return 0;
                    }
                    /* The first row is completely visible, return the
                     * height of the previous row.
                     */
                    else if (r.y == visibleRect.y) {
                        Rectangle prevR = getCellBounds(row - 1, row - 1);
                        return (prevR== null) ? 0 : prevR.height;
                    }
                    /* The first row is partially visible, return the
                     * height of hidden part.
                     */
                    else {
                        return visibleRect.y - r.y;
                    }
                }
            }
        }
    }


    /**
     * Returns the block increment amount.
     *
     * @param visibleRect  the visible rectangle
     * @param orientation  HORIZONTAL or VERTICAL  
     * @param direction    if <= 0, then scroll UP; if > 0, then scroll DOWN
     * @return the visibleRect.height or visibleRect.width per the orientation
     * @see Scrollable#getScrollableUnitIncrement
     * @throws IllegalArgumentException   if visibleRect is <code>null</code>, or
     *            orientation isn't one of SwingConstants.VERTICAL,
     *            SwingConstants.HORIZONTAL.
     * 
     */
    public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
	checkScrollableParameters(visibleRect, orientation);
        return (orientation == SwingConstants.VERTICAL) ? visibleRect.height : visibleRect.width;
    }


    /**
     * Returns true if this <code>JList</code> is displayed in a 
     * <code>JViewport</code> and the viewport is wider than
     * <code>JList</code>'s preferred width; otherwise returns false.
     * If false, then don't track the viewport's width. This allows horizontal
     * scrolling if the <code>JViewport</code> is itself embedded in a
     * <code>JScrollPane</code>.
     *
     * @return true if viewport is wider than the <code>JList</code>'s
     *				preferred width, otherwise false
     * @see Scrollable#getScrollableTracksViewportWidth
     */
    public boolean getScrollableTracksViewportWidth() {
	if (getParent() instanceof JViewport) {
	    return (((JViewpor