Run the testcase below
and notice that a popup appears when you run it under the JDK 1.6 or later

run it with 1.5 and you'll see no popups,
so it is a regression

import javax.swing.*;
public class theBug {
    public static void main(String[] args) throws Exception {
        ProgressMonitor pm = new ProgressMonitor(null, "Message", "note", 0, 100);
        pm.setMillisToPopup(0);
        pm.setMillisToDecideToPopup(0);
        // this line causes popup to appear in 1.6 but not in 1.5
        pm.setProgress(0);
    }
}