that not possible directly, its very hard to override known bug, in other hands Swing doesn't allows two lightwieght popup components in same time
import javax.swing.*;
import java.awt.event.*;
public class Test {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setSize(400, 400);
frame.setVisible(true);
String[] list = {"1", "2", "3", "4",};
JComboBox comb = new JComboBox(list);
final JPopupMenu pop = new JPopupMenu();
pop.add(comb);
frame.addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
System.out.println("mousePressed");
pop.show(e.getComponent(), e.getX(), e.getY());
}
});
}
}
but workaround is very simple use JWindows
or un-decorated JDialog
with JComboBox
instead of JPopup