function hideFields(){
    //document.getElementById('via_email').checked = true;
	showAddress();
}

function showAddress(){
	if(!document.getElementById('via_email')) return false;
	if(!document.getElementById('via_mail')) return false;
    if(!document.getElementById('email')) return false;
	if(!document.getElementById('address')) return false;

	if (document.getElementById('via_email').checked)
		document.getElementById('email').style.display = "block";
    else{
        document.getElementById('email').style.display = "none";

        for(i=0; i<document.getElementById('email').getElementsByTagName('input').length; i++){
            if(document.getElementById('email').getElementsByTagName('input')[i].type == "text"){
                document.getElementById('email').getElementsByTagName('input')[i].value = "";
            }
        }
    }

	if (document.getElementById('via_mail').checked)
		document.getElementById('address').style.display="block";
    else{
        document.getElementById('address').style.display="none";

        for(i=0; i<document.getElementById('address').getElementsByTagName('input').length; i++){
            if(document.getElementById('address').getElementsByTagName('input')[i].type == "text"){
                document.getElementById('address').getElementsByTagName('input')[i].value = "";
            }
        }
    }

    return true;
}


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 += 96;
  wleft = (screen.width - w) / 2;
  wtop = (screen.height - h) / 2;
  // IE5 and other old browsers might allow a window that is
  // partially offscreen or wider than the screen. Fix that.
  // (Newer browsers fix this for us, but let's be thorough.)
  if (wleft < 0) {
    w = screen.width;
    wleft = 0;
  }
  if (wtop < 0) {
    h = screen.height;
    wtop = 0;
  }
  var win = window.open(url,
    name,
    'width=' + w + ', height=' + h + ', ' +
    'left=' + wleft + ', top=' + wtop + ', ' +
    'location=no, menubar=no, ' +
    'status=yes, toolbar=no, scrollbars=yes, resizable=yes');
  // 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();
}