Steps to reproduce:

Select an item in a List,
Click the middle mouse button.

The system should lock up now, the cursor freezes in the drag and
drop form.

Below is the List example from "The Java Class Libraries, Vol 2"

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

class Main extends Frame implements ActionListener, ItemListener {
    final static int ITEMS = 10;
    List ltList = new List(ITEMS, true);
    List rtList = new List(0, true);

    Main() {
        super("List Example");
        GridBagLayout gbl = new GridBagLayout();

        setLayout(gbl);
        add(ltList, 0, 0, 1, 5, 1.0, 1.0);
        add(rtList, 2, 0, 1, 5, 1.0, 1.0);
        // Add action and item listeners to list
        ltList.addActionListener(this);
        ltList.addItemListener(this);
        rtList.addActionListener(this);
        rtList.addItemListener(this);

        // Create buttons for adding/removing items from lists
        Button b;
        add(b = new Button(">"), 1, 0, 1, 1, 0, 1.0);
        b.addActionListener(this);
        add(b = new Button(">>"), 1, 1, 1, 1, 0, 1.0);
        b.addActionListener(this);
        add(b = new Button("<"), 1, 2, 1, 1, 0, 1.0);
        b.addActionListener(this);
        add(b = new Button("<<"), 1, 3, 1, 1, 0, 1.0);
        b.addActionListener(this);
        add(b = new Button("!"), 1, 4, 1, 1, 0, 1.0);
        b.addActionListener(this);

        for (int i=0; i<ITEMS; i++) {
           ltList.add("item "+i);
        }
        pack();
        show();
    }

    void add(Component comp,
            int x, int y, int w, int h, double weightx, double weighty) {
        GridBagLayout gbl = (GridBagLayout)getLayout();
        GridBagConstraints c = new GridBagConstraints();

        c.fill = GridBagConstraints.BOTH;
        c.gridx = x;
        c.gridy = y;
        c.gridwidth = w;
        c.gridheight = h;
        c.weightx = weightx;
        c.weighty = weighty;
        add(comp);
        gbl.setConstraints(comp, c);
    }

    void reverseSelections(List l) {
        for (int i=0; i<l.getItemCount(); i++) {
            if (l.isIndexSelected(i)) {
                l.deselect(i);
            } else {
                l.select(i);
            }
        }
    }

    void deselectAll(List l) {
        for (int i=0; i<l.getItemCount(); i++) {
            l.deselect(i);
        }
    }

    void replaceItem(List l, String item) {
        for (int i=0; i<l.getItemCount(); i++) {
            if (l.getItem(i).equals(item)) {
                l.replaceItem(item + "*", i);
            }
        }
    }

    void move(List l1, List l2, boolean all) {
        if (all) {
            for (int i=0; i<l1.getItemCount(); i++) {
                l2.add(l1.getItem(i));
            }
            l1.removeAll();
        } else {
            String[] items = l1.getSelectedItems();
            int[] itemIndexes = l1.getSelectedIndexes();

            deselectAll(l2);
            for (int i=0; i<items.length; i++) {
                l2.add(items[i]); // add it
                l2.select(l2.getItemCount()-1);// and select it
                if (i == 0) {
                    l2.makeVisible(l2.getItemCount()-1);
                }
            }
            for (int i=itemIndexes.length-1; i>=0; i--) {
                l1.remove(itemIndexes[i]);
            }
        }
    }

    public void actionPerformed(ActionEvent evt) {
        String arg = evt.getActionCommand();
        if (">".equals(arg)) {
            move(ltList, rtList, false);
        } else if (">>".equals(arg)) {
            move(ltList, rtList, true);
        } else if ("<".equals(arg)) {
            move(rtList, ltList, false);
        } else if ("<<".equals(arg)) {
            move(rtList, ltList, true);
        } else if ("!".equals(arg)) {
            if (ltList.getSelectedItems().length > 0) {
                reverseSelections(ltList);
            } else if (rtList.getSelectedItems().length > 0) {
                reverseSelections(rtList);
            }
        } else {
            Object target = evt.getSource();
            if (target == rtList || target == ltList) {
                replaceItem((List)target, arg);
            }
        }
    }

    public void itemStateChanged(ItemEvent evt) {
        List target = (List)evt.getSource();
        if (target == ltList) {
            deselectAll(rtList);
        } else if (target == rtList) {
            deselectAll(ltList);
        }
    }

    public static void main(String[] args) {
        new Main();
    }
}