[cyber]

function addEvent( elem, evt, listener ) {
	if ( elem.addEventListener ) {
		elem.addEventListener( evt, listener, false );
	} else if ( elem.attachEvent ) {
		elem.attachEvent( 'on' + evt, function() {
			listener.call( elem, window.event );
		});
	}
}

addEvent( document.getElementById('combo_1'), "focus", function( event ){
    tatarcha.comboChange(event,true);
});

а в чем разница ?