function abreJanela( url , nome , w , h )
{
	var win = null;
	var w = w;
	var h = h;
	LeftPosition = (screen.width) ? (screen.width-w)/2 : 0;
	TopPosition = (screen.height) ? (screen.height-h)/2 : 0;
	win = window.open( url , nome , 'width=' + w + ', height=' + h + ', top=' + TopPosition + ', left=' + LeftPosition + ',scrollbars=no' );
}