Overriding Default JTable Selection Behavior

Question

I'm attempting to override the default selection behavior of a JTable. For clicking, I want the table to behave basically as if the ctrl key was being held down all the time. That works great.
I want the behavior of dragging a selection to behave a certain way as well. If ctrl is not held down, then a drag should cancel the current selection and start a new one at the drag interval. This works fine too.
However, if ctrl is held down during a drag, I want the dragged interval to be added to the selection instead of replacing it. This almost works. However, if I hold ctrl while dragging, it no longer let's me "undrag" the selection: once a cell is inside the dragged interval, it's selected, even if you drag back over it to deselect it.
I understand why that's happening given my approach, but I'm looking for a way around it. Does anybody have any ideas about how to get a JTable to behave the way I want?
Here's a compilable program that demonstrates what I'm doing:
import javax.swing.*;
import java.awt.event.*;
public class TestTableSelection{
     boolean ctrlDown = false;
     JTable table;
     public TestTableSelection(){
          JFrame frame = new JFrame("Test Table Selection");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          //give the table random data
          String [][] data = new String [10][5];
          String [] names = new String [5];
          for(int i = 0; i < 5; i++){
               names[i] = "C: " + i;
               for(int j = 0; j < 10; j++){
                    data[j] = "t: " + (int)(Math.random()*100);
          table = new JTable(data, names){
               //override the default selection behavior
               public void changeSelection(int rowIndex, int columnIndex, boolean toggle, boolean extend) {
                    if(ctrlDown){
                         //ctrl + dragging should add the dragged interval to the selection
                         super.changeSelection(rowIndex, columnIndex, toggle, extend);     
                    else{
                         //clicking adds a row to the selection without clearing others
                         //dragging without holding ctrl clears the selection
                         //and starts a new selection at the dragged interval
                         super.changeSelection(rowIndex, columnIndex, !extend, extend);
          //keep track of when ctrl is held down
          table.addKeyListener(new KeyAdapter() {
               public void keyPressed(KeyEvent e) {
                    ctrlDown = e.isControlDown();
               public void keyReleased(KeyEvent e){
                    ctrlDown = e.isControlDown();
          frame.getContentPane().add(new JScrollPane(table));
          frame.setSize(250, 250);
          frame.setVisible(true);
     public static void main(String[] args){
          new TestTableSelection();
Let me know if any of that isn't clear.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Answer 1

This change seemed to work for me
          table = new JTable(data, names){
               int prevRow = -1;
               //override the default selection behavior
               public void changeSelection(int rowIndex, int columnIndex, boolean toggle, boolean extend) {
                    if(ctrlDown){
                         //ctrl + dragging should add the dragged interval to the selection
                         if ( rowIndex != prevRow ) {
                              prevRow = rowIndex;
                              super.changeSelection(rowIndex, columnIndex, true, false);
                    else{
                         //clicking adds a row to the selection without clearing others
                         //dragging without holding ctrl clears the selection
                         //and starts a new selection at the dragged interval
                         super.changeSelection(rowIndex, columnIndex, !extend, extend);
          };