public void installUI(JComponent c){
  MouseListener[] ml=c.getMouseListeners();
  super.installUI(c);
  c.setOpaque(false);
  for (int i=0; i < ml.length; i++) {
    arrowButton.addMouseListener(ml[i]);
  }
}

public void installUI ( JComponent c ) { MouseListener [ ] ml = c . getMouseListeners ( ) ; super . installUI ( c ) ; c . setOpaque ( false ) ; for ( int i = 0 ; i < ml . length ; i ++ ) { arrowButton . addMouseListener ( ml [ i ] ) ; } }
install ui - set combobox opaque . bug in metal : arrowbutton gets mouse events , so add the jcombobox mouselisteners to the arrowbutton
