function checkMail(form,email_field)
{
	var x = document.forms[form].email_field.value;
	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (!filter.test(x)) alert('Please provide a valid email address.');
}


function popup(URL,NAME,ATTR) 
{
    gallery_window = window.open(URL,NAME,ATTR);
    gallery_window.focus();

}

// Adapted from script at js-examples.com
// Usage: <a href="http://www.url.com/" onclick="NewWindow(this.href,'name','400','400','yes');return false"></a>
function centeredWindow(mypage,myname,w,h,scroll)
{
  var winl = (screen.width-w)/2;
  var wint = (screen.height-h)/2;
  var settings  ='height='+h+',';
      settings +='width='+w+',';
      settings +='top='+wint+',';
      settings +='left='+winl+',';
      settings +='scrollbars='+scroll+',';
      settings +='resizable=yes';
  win=window.open(mypage,myname,settings);
  if(parseInt(navigator.appVersion) >= 4){win.window.focus();}
}