function ShowBox(strBoxNr)
   {
        if ( strBoxNr == "all" )
        {
            var i = 1;
            var objBox = document.getElementById( "box" + i );
            while ( objBox )
            {
                objBox.style.display = "block";
                objBox = document.getElementById( "box" + ( ++i ) );
            }
        }
        else
        {
            if ( isNaN( strBoxNr ) )
            {
                alert( 'Invalid argument!' );
                return;
            }
            
            var i = 1;
            var objBox = document.getElementById( "box" + i );
            while ( objBox )
            {
                objBox.style.display = ( i == strBoxNr ? "block" : "none" );
                objBox = document.getElementById( "box" + ( ++i ) );
            }
        }
   }