// JavaScript Document
function wopen(url, name, w, h)
{
  // Fudge factors for window decoration space.
  // In my tests these work well on all platforms & browsers.
  w += 32;
  h += 54;
  wleft = (screen.width - w) / 2;
  wtop = (screen.height - h) / 2;
  var win = window.open(url,
    name,
    'width=' + w + ', height=' + h + ', ' +
    'left=' + wleft + ', top=' + wtop + ', ' +
    'location=no, menubar=no, ' +
    'status=no, toolbar=no, scrollbars=no, resizable=no');
  // Just in case width and height are ignored
  win.resizeTo(w, h);
  // Just in case left and top are ignored
  win.moveTo(wleft, wtop);
  win.focus();
}

function isNumberKey(evt) {
	var charCode = (evt.which) ? evt.which : event.keyCode

	if (charCode > 31 && (charCode < 48 || charCode > 57))
		return false;

	return true;
}

function isDecimalKey(evt) {
	var charCode = (evt.which) ? evt.which : event.keyCode

	if (charCode == 46) // Decimal Period
		return true;

	if (charCode > 31 && (charCode < 48 || charCode > 57))
		return false;

	return true;
}

function isQuantityKey(evt) {
	var charCode = (evt.which) ? evt.which : event.keyCode

	if (charCode == 43 || charCode == 45) // + or - key
		return true;

	if (charCode > 31 && (charCode < 48 || charCode > 57))
		return false;

	return true;
}