function addEvent( obj, type, fn )
{
    if ( obj.attachEvent )
    {
        obj['e'+type+fn] = fn;
        obj[type+fn] = function(){obj['e'+type+fn]( window.event );}
        obj.attachEvent( 'on'+type, obj[type+fn] );
    }
    else
    {
        obj.addEventListener( type, fn, false );
    }
}

function removeEvent( obj, type, fn )
{
    if ( obj.detachEvent )
    {
        obj.detachEvent( 'on'+type, obj[type+fn] );
        obj[type+fn] = null;
    }
    else
    {
        obj.removeEventListener( type, fn, false );
    }
}