if (document.images) {
    lbuttonup       = new Image();
    lbuttonup.src   = "images/lbutton.jpg" ;
    lbuttondown     = new Image() ;
    lbuttondown.src = "images/lbuttondown.jpg" ;
	rbuttonup       = new Image();
	rbuttonup.src   = "images/rbutton.jpg" ;
	rbuttondown     = new Image() ;
	rbuttondown.src = "images/rbuttondown.jpg" ;
	hhbuttonup       = new Image();
	hhbuttonup.src   = "images/hhbutton.jpg" ;
	hhbuttondown     = new Image() ;
	hhbuttondown.src = "images/hhbuttondown.jpg" ;
}
function buttondown( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "down.src" );
    }
}
function buttonup ( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "up.src" );
    }
}