public void popupMenuWillBecomeInvisible(PopupMenuEvent ev) {
Point cpos = combo1.getLocation();
SwingUtilities.convertPointToScreen(cpos, panel);
JPopupMenu pm = (JPopupMenu) combo1.getUI().getAccessibleChild(combo1, 0);
if (pm != null) {
Point p = pm.getLocation();
SwingUtilities.convertPointToScreen(p, pm);
if (p.y < cpos.y) {
throw new RuntimeException("ComboBox popup is wrongly aligned");
} // check that popup was opened down
}
}
