oldWidth = cmb.getSize().width;
cmb.setSize(500, cmb.getHeight());
// If it pops up now JPopupMenu will still be short
// Fire popupMenuCanceled...
if (!stateCmb)
cmb.firePopupMenuCanceled();
// Reset JComboBox and state
stateCmb = false;
cmb.setSize(oldWidth, cmb.getHeight());
}